@article{pmid34302049,
title = {3D test sample for the calibration and quality control of stimulated emission depletion (STED) and confocal microscopes},
author = {Ernest B van der Wee and Jantina Fokkema and Chris L Kennedy and Marc Del Pozo and D A Matthijs de Winter and Peter N A Speets and Hans C Gerritsen and Alfons van Blaaderen},
doi = {10.1038/s42003-021-02432-3},
issn = {2399-3642},
year  = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
journal = {Commun Biol},
volume = {4},
number = {1},
pages = {909},
abstract = {Multiple samples are required to monitor and optimize the quality and reliability of quantitative measurements of stimulated emission depletion (STED) and confocal microscopes. Here, we present a single sample to calibrate these microscopes, align their laser beams and measure their point spread function (PSF) in 3D. The sample is composed of a refractive index matched colloidal crystal of silica beads with fluorescent and gold cores. The microscopes can be calibrated in three dimensions using the periodicity of the crystal; the alignment of the laser beams can be checked using the reflection of the gold cores; and the PSF can be measured at multiple positions and depths using the fluorescent cores. It is demonstrated how this sample can be used to visualize and improve the quality of STED and confocal microscopy images. The sample is adjustable to meet the requirements of different NA objectives and microscopy techniques and additionally can be used to evaluate refractive index mismatches as a function of depth quantitatively.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{ASLANNEJAD2021106054,
title = {Liquid droplet imbibition into a thin coating layer: Direct pore-scale modeling and experimental observations},
author = {H. Aslannejad and Sergey V. Loginov and B. Hoek and E. M. Schoonderwoerd and Hans C Gerritsen and S. M. Hassanizadeh},
url = {https://www.sciencedirect.com/science/article/pii/S0300944020312650},
doi = {https://doi.org/10.1016/j.porgcoat.2020.106054},
issn = {0300-9440},
year  = {2021},
date = {2021-01-01},
journal = {Progress in Organic Coatings},
volume = {151},
pages = {106054},
abstract = {In order to control ink droplet movement into the printing-paper layer, a set of pore-scale two-phase flow simulations were performed. The high-resolution three-dimensional pore space of the paper was obtained using focused ion beam scanning electron microscopy (FIB-SEM). Solving Navier-Stokes equations yielded details about dynamic movement of a droplet into the layer. To evaluate simulation results, for the first time, confocal laser microscopy imaging technique was integrated into a FIB-SEM chamber. Doing so, high resolution imaging of the droplet penetration inside paper was conducted and computed volume of penetrated ink at final stage was compared to the imaged volume. The ink penetration and spreading extent showed a good agreement with simulation results. Therefore, the developed simulation case was further investigated to study impact of liquid contact angle, real ink properties, and droplet arrival velocity on paper surface on final print quality. A faster penetration into the paper coating was observed for smaller equilibrium contact angles; meanwhile, more radial wicking was observed. In case of velocity of impact, higher velocity caused creation of irregular shapes of the ink footprint on paper surface. In addition to that, higher velocity caused ink splash which consequently created satellite droplets and lowered the print quality. Comparing ink-like liquid (representing real ink liquid properties) with water, water moves faster than ink-like liquid into the paper. This is mainly due to the higher viscosity and lower surface tension of the ink-like liquid.},
keywords = {CLSM, Coated paper, Droplet, Focused ion beam SEM, Imbibition, Ink, OpenFOAM, Pore-scale modeling, Printing paper, Spreading, Wicking},
pubstate = {published},
tppubtype = {article}
}
@article{doi:10.1021/acs.chemmater.0c02817,
title = {Seeded Growth Combined with Cation Exchange for the Synthesis of Anisotropic Cu2–xS/ZnS, Cu2–xS, and CuInS2 Nanorods},
author = {Chenghui Xia and Adrian Pedrazo-Tardajos and Da Wang and Johannes D. Meeldijk and Hans C. Gerritsen and Sara Bals and Celso Mello Donega},
url = {https://doi.org/10.1021/acs.chemmater.0c02817},
doi = {10.1021/acs.chemmater.0c02817},
year  = {2021},
date = {2021-01-01},
journal = {Chemistry of Materials},
volume = {33},
number = {1},
pages = {102-116},
abstract = {Colloidal copper(I) sulfide (Cu2–xS) nanocrystals (NCs) have attracted much attention for a wide range of applications because of their unique optoelectronic properties, driving scientists to explore the potential of using Cu2–xS NCs as seeds in the synthesis of heteronanocrystals to achieve new multifunctional materials. Herein, we developed a multistep synthesis strategy toward Cu2–xS/ZnS heteronanorods. The Janus-type Cu2–xS/ZnS heteronanorods are obtained by the injection of hexagonal high-chalcocite Cu2–xS seed NCs in a hot zinc oleate solution in the presence of suitable surfactants, 20 s after the injection of sulfur precursors. The Cu2–xS seed NCs undergo rapid aggregation and coalescence in the first few seconds after the injection, forming larger NCs that act as the effective seeds for heteronucleation and growth of ZnS. The ZnS heteronucleation occurs on a single (100) facet of the Cu2–xS seed NCs and is followed by fast anisotropic growth along a direction that is perpendicular to the c-axis, thus leading to Cu2–xS/ZnS Janus-type heteronanorods with a sharp heterointerface. Interestingly, the high-chalcocite crystal structure of the injected Cu2–xS seed NCs is preserved in the Cu2–xS segments of the heteronanorods because of the high-thermodynamic stability of this Cu2–xS phase. The Cu2–xS/ZnS heteronanorods are subsequently converted into single-component Cu2–xS and CuInS2 nanorods by postsynthetic topotactic cation exchange. This work expands the possibilities for the rational synthesis of colloidal multicomponent heteronanorods by allowing the design principles of postsynthetic heteroepitaxial seeded growth and nanoscale cation exchange to be combined, yielding access to a plethora of multicomponent heteronanorods with diameters in the quantum confinement regime.},
note = {PMID: 33456135},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@incollection{BUERGER2021171,
title = {Chapter 8 - On-section correlative light and electron microscopy of large cellular volumes using STEM tomography},
author = {Korbinian Buerger and Kerstin N. Schmidt and Jantina Fokkema and Hans C. Gerritsen and Olga Maier and Uwe Vries and Yulia Zaytseva and Reinhard Rachel and Ralph Witzgall},
editor = {Thomas Müller-Reichert and Paul Verkade},
url = {https://www.sciencedirect.com/science/article/pii/S0091679X2030176X},
doi = {https://doi.org/10.1016/bs.mcb.2020.09.002},
issn = {0091-679X},
year  = {2021},
date = {2021-01-01},
booktitle = {Correlative Light and Electron Microscopy IV},
volume = {162},
pages = {171-203},
publisher = {Academic Press},
series = {Methods in Cell Biology},
abstract = {The application of both fluorescence and electron microscopy results in a powerful combination of imaging modalities called “correlative light and electron microscopy” (CLEM). Whereas conventional transmission electron microscopy (TEM) tomography is only able to image sections up to a thickness of ~300nm, scanning transmission electron microscopy (STEM) tomography at 200kV allows the analysis of sections up to a thickness of 900nm in three dimensions. In the current study we have successfully integrated STEM tomography into CLEM as demonstrated for human retinal pigment epithelial 1 (RPE1) cells expressing various fluorescent fusion proteins which were high-pressure frozen and then embedded in Lowicryl HM20. Fluorescently labeled gold nanoparticles were applied onto resin sections and imaged by fluorescence and electron microscopy. STEM tomograms were recorded at regions of interest, and overlays were generated using the eC-CLEM software package. Through the nuclear staining of living cells, the use of fluorescently labeled gold fiducials for the generation of overlays, and the integration of STEM tomography we have markedly extended the application of the Kukulski protocol (Kukulski et al., 2011, 2012). Various fluorescently tagged proteins localizing to different cellular organelles could be assigned to their ultrastructural compartments. By combining STEM tomography with on-section CLEM, fluorescently tagged proteins can be localized in three-dimensional ultrastructural environments with a volume of at least 2.7×2.7×0.5μm.},
keywords = {Correlative light and electron microscopy (CLEM), Fibroblast growth factor receptor 1 (FGFR1), Fluorescently labeled gold nanoparticles, Primary cilium, Retinal pigment epithelial (RPE1) cells, Scanning transmission electron microscopy (STEM) tomography},
pubstate = {published},
tppubtype = {incollection}
}
@article{lehmann_optical_2020,
title = {Optical Tweezers Approaches for Probing Multiscale Protein Mechanics and Assembly},
author = {K Lehmann and M Shayegan and Gerhard A. Blab and N R Forde},
url = {https://www.frontiersin.org/articles/10.3389/fmolb.2020.577314/full},
doi = {10.3389/fmolb.2020.577314},
year  = {2020},
date = {2020-01-01},
urldate = {2020-01-01},
journal = {Frontiers in Molecular Biosciences},
volume = {7},
keywords = {Collagen, Fibrillar proteins, microrheology, Optical tweezers (OT), Protein assemblies, Protein mechanics, protein structure / folding, Single-molecule},
pubstate = {published},
tppubtype = {article}
}
@article{mohammadian_integrated_2020,
title = {Integrated super resolution fluorescence microscopy and transmission electron microscopy},
author = {Sajjad Mohammadian and Alexandra V Agronskaia and Gerhard A. Blab and E G van Donselaar and C de Heus and N Liv and J Klumperman and Hans C. Gerritsen},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85085254573&doi=10.1016%2fj.ultramic.2020.113007&partnerID=40&md5=d0486d73138b228cf6091bd2e59de054},
doi = {10.1016/j.ultramic.2020.113007},
year  = {2020},
date = {2020-01-01},
journal = {Ultramicroscopy},
volume = {215},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{soeteman-hernandez_challenges_2020,
title = {Challenges of implementing nano-specific safety and safe-by-design principles in academia},
author = {L G Soeteman-Hernández and Gerhard A. Blab and A Carattino and F Dekker and S Dekkers and M van der Linden and A van Silfhout and C W Noorlander},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089135360&doi=10.1016%2fj.impact.2020.100243&partnerID=40&md5=95e711c68da63f49c51e21c9a9b22648},
doi = {10.1016/j.impact.2020.100243},
year  = {2020},
date = {2020-01-01},
journal = {NanoImpact},
volume = {19},
keywords = {Academia, Responsible research and innovation, Safe-by-design},
pubstate = {published},
tppubtype = {article}
}
@article{van_hest_towards_2019,
title = {Towards robust and versatile single nanoparticle fiducial markers for correlative light and electron microscopy},
author = { Jacobine J.H.A. van Hest and Alexandra V. Agronskaia and Jantina Fokkema and F. Montanarella and A. Gregorio Puig and Celso de Mello Donega and Andries Meijerink and Gerhard A. Blab and Hans C. Gerritsen},
doi = {10.1111/jmi.12778},
year  = {2019},
date = {2019-01-01},
journal = {Journal of Microscopy},
volume = {274},
number = {1},
pages = {13--22},
abstract = {Fiducial markers are used in correlated light and electron microscopy (CLEM) to enable accurate overlaying of fluorescence and electron microscopy images. Currently used fiducial markers, e.g. dye-labelled nanoparticles and quantum dots, suffer from irreversible quenching of the luminescence after electron beam exposure. This limits their use in CLEM, since samples have to be studied with light microscopy before the sample can be studied with electron microscopy. Robust fiducial markers, i.e. luminescent labels that can (partially) withstand electron bombardment, are interesting because of the recent development of integrated CLEM microscopes. In addition, nonintegrated CLEM setups may benefit from such fiducial markers. Such markers would allow switching back from EM to LM and are not available yet. Here, we investigate the robustness of various luminescent nanoparticles (NPs) that have good contrast in electron microscopy; 130 nm gold-core rhodamine B-labelled silica particles, 15 nm CdSe/CdS/ZnS core–shell–shell quantum dots (QDs) and 230 nm Y 2 O 3 :Eu 3+ particles. Robustness is studied by measuring the luminescence of (single) NPs after various cycles of electron beam exposure. The gold-core rhodamine B-labelled silica NPs and QDs are quenched after a single exposure to 60 ke −  nm –2 with an energy of 120 keV, while Y 2 O 3 :Eu 3+ NPs are robust and still show luminescence after five doses of 60 ke − nm –2 . In addition, the luminescence intensity of Y 2 O 3 :Eu 3+ NPs is investigated as function of electron dose for various electron fluxes. The luminescence intensity initially drops to a constant value well above the single particle detection limit. The intensity loss does not depend on the electron flux, but on the total electron dose. The results indicate that Y 2 O 3 :Eu 3+ NPs are promising as robust fiducial marker in CLEM. Lay Description: Luminescent particles are used as fiducial markers in correlative light and electron microscopy (CLEM) to enable accurate overlaying of fluorescence and electron microscopy images. The currently used fiducial markers, e.g. dyes and quantum dots, loose their luminescence after exposure to the electron beam of the electron microscope. This limits their use in CLEM, since samples have to be studied with light microscopy before the sample can be studied with electron microscopy. Robust fiducial markers, i.e. luminescent labels that can withstand electron exposure, are interesting because of recent developments in integrated CLEM microscopes. Also nonintegrated CLEM setups may benefit from such fiducial markers. Such markers would allow for switching back to fluorescence imaging after the recording of electron microscopy imaging and are not available yet. Here, we investigate the robustness of various luminescent nanoparticles (NPs) that have good contrast in electron microscopy; dye-labelled silica particles, quantum dots and lanthanide-doped inorganic particles. Robustness is studied by measuring the luminescence of (single) NPs after various cycles of electron beam exposure. The dye-labelled silica NPs and QDs are quenched after a single exposure to 60 ke − nm –2 with an energy of 120 keV, while lanthanide-doped inorganic NPs are robust and still show luminescence after five doses of 60 ke − nm –2 . In addition, the luminescence intensity of lanthanide-doped inorganic NPs is investigated as function of electron dose for various electron fluxes. The luminescence intensity initially drops to a constant value well above the single particle detection limit. The intensity loss does not depend on the electron flux, but on the total electron dose. The results indicate that lanthanide-doped NPs are promising as robust fiducial marker in CLEM. © 2019 The Authors. Journal of Microscopy published by JohnWiley & Sons Ltd on behalf of Royal Microscopical Society.},
keywords = {Correlative microscopy, Fiducial Markers, integrated correlative microscopy, lanthanides, luminescence},
pubstate = {published},
tppubtype = {article}
}
@article{mohammadian_high_2019,
title = {High accuracy, fiducial marker-based image registration of correlative microscopy images},
author = {Sajjad Mohammadian and Jantina Fokkema and Alexandra V Agronskaia and N Liv and C de Heus and E van Donselaar and Gerhard A. Blab and J Klumperman and Hans C Gerritsen},
doi = {10.1038/s41598-019-40098-4},
year  = {2019},
date = {2019-01-01},
journal = {Scientific Reports},
volume = {9},
number = {1},
abstract = {Fluorescence microscopy (FM) and electron microscopy (EM) are complementary techniques. FM affords examination of large fields of view and identifying regions of interest but has a low resolution. EM exhibits excellent resolution over a limited field of view. The combination of these two techniques, correlative microscopy, received considerable interest in the past years and has proven its potential in biology and material science. Accurate correlation of FM and EM images is, however, challenging due to the differences in contrast mechanism, size of field of view and resolution. We report an accurate, fast and robust method to correlate FM and EM images using low densities of fiducial markers. Here, 120 nm diameter fiducial markers consisting of fluorescently labelled silica coated gold nanoparticles are used. The method relies on recording FM, low magnification EM and high magnification EM images. Two linear transformation matrices are constructed, FM to low magnification EM and low magnification EM to high magnification EM. Combination of these matrices results in a high accuracy transformation of FM to high magnification EM coordinates. The method was tested using two different transmission electron microscopes and different Tokuyasu and Lowicryl sections. The overall accuracy of the correlation method is high, 5–30 nm. © 2019, The Author(s).},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Fokkema2018,
title = {Fluorescently Labelled Silica Coated Gold Nanoparticles as Fiducial Markers for Correlative Light and Electron Microscopy},
author = {Jantina Fokkema and Job Fermie and Nalan Liv and Dave J. van den Heuvel and Tom O. M. Konings and Gerhard A. Blab and Andries Meijerink and Judith Klumperman and Hans C. Gerritsen},
url = {https://doi.org/10.1038/s41598-018-31836-1},
doi = {10.1038/s41598-018-31836-1},
year  = {2018},
date = {2018-09-11},
journal = {Scientific Reports},
volume = {8},
number = {1},
pages = {13625},
abstract = {In this work, gold nanoparticles coated with a fluorescently labelled (rhodamine B) silica shell are presented as fiducial markers for correlative light and electron microscopy (CLEM). The synthesis of the particles is optimized to obtain homogeneous, spherical core-shell particles of arbitrary size. Next, particles labelled with different fluorophore densities are characterized to determine under which conditions bright and (photo)stable particles can be obtained. 2 and 3D CLEM examples are presented where optimized particles are used for correlation. In the 2D example, fiducials are added to a cryosection of cells whereas in the 3D example cells are imaged after endocytosis of the fiducials. Both examples demonstrate that the particles are clearly visible in both modalities and can be used for correlation. Additionally, the recognizable core-shell structure of the fiducials proves to be very powerful in electron microscopy: it makes it possible to irrefutably identify the particles and makes it easy to accurately determine the center of the fiducials.},
keywords = {Correlated Microscopy, Fiducial Markers, Fluorescence Microscopy, Integrated Microscopy},
pubstate = {published},
tppubtype = {article}
}
@article{fermie_CLEM,
title = {Single organelle dynamics linked to 3D structure by correlative live-cell imaging and 3D electron microscopy},
author = { Job Fermie and Nalan Liv and Corlinda ten Brink and Elly G. van Donselaar and Wally H. Müller and Nicole L. Schieber and Yannick Schwab and Hans C. Gerritsen and Judith Klumperman},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/tra.12557},
doi = {10.1111/tra.12557},
year  = {2018},
date = {2018-02-16},
journal = {Traffic},
volume = {19},
number = {5},
pages = {354-369},
abstract = {Live-cell correlative light-electron microscopy (live-cell-CLEM) integrates live movies with the corresponding electron microscopy (EM) image, but a major challenge is to relate the dynamic characteristics of single organelles to their 3-dimensional (3D) ultrastructure. Here, we introduce focused ion beam scanning electron microscopy (FIB-SEM) in a modular live-cell-CLEM pipeline for a single organelle CLEM. We transfected cells with lysosomal-associated membrane protein 1-green fluorescent protein (LAMP-1-GFP), analyzed the dynamics of individual GFP-positive spots, and correlated these to their corresponding fine-architecture and immediate cellular environment. By FIB-SEM we quantitatively assessed morphological characteristics, like number of intraluminal vesicles and contact sites with endoplasmic reticulum and mitochondria. Hence, we present a novel way to integrate multiple parameters of subcellular dynamics and architecture onto a single organelle, which is relevant to address biological questions related to membrane trafficking, organelle biogenesis and positioning. Furthermore, by using CLEM to select regions of interest, our method allows for targeted FIB-SEM, which significantly reduces time required for image acquisition and data processing.},
keywords = {correlative light-electron microscopy, endolysosomal system, focused ion beam scanning electron microscopy, organelle dynamics, time-lapse microscopy, volume electron microscopy},
pubstate = {published},
tppubtype = {article}
}
@article{Xia20185755,
title = {Near-Infrared-Emitting CuInS2/ZnS Dot-in-Rod Colloidal Heteronanorods by Seeded Growth},
author = { Cheng-Hui Xia and N. Winckelmans and P.T. Prins and S. Bals and Hans C. Gerritsen and Celso De Mello Donega},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045217473&doi=10.1021%2fjacs.8b01412&partnerID=40&md5=8e0bd7ee2930338cdc574ced9a3b77ca},
doi = {10.1021/jacs.8b01412},
year  = {2018},
date = {2018-01-01},
journal = {Journal of the American Chemical Society},
volume = {140},
number = {17},
pages = {5755-5763},
abstract = {Synthesis protocols for anisotropic CuInX2 (X = S, Se, Te)-based heteronanocrystals (HNCs) are scarce due to the difficulty in balancing the reactivities of multiple precursors and the high solid-state diffusion rates of the cations involved in the CuInX2 lattice. In this work, we report a multistep seeded growth synthesis protocol that yields colloidal wurtzite CuInS2/ZnS dot core/rod shell HNCs with photoluminescence in the NIR (∼800 nm). The wurtzite CuInS2 NCs used as seeds are obtained by topotactic partial Cu+ for In3+ cation exchange in template Cu2-xS NCs. The seed NCs are injected in a hot solution of zinc oleate and hexadecylamine in octadecene, 20 s after the injection of sulfur in octadecene. This results in heteroepitaxial growth of wurtzite ZnS primarily on the Sulfur-terminated polar facet of the CuInS2 seed NCs, the other facets being overcoated only by a thin (∼1 monolayer) shell. The fast (∼21 nm/min) asymmetric axial growth of the nanorod proceeds by addition of [ZnS] monomer units, so that the polarity of the terminal (002) facet is preserved throughout the growth. The delayed injection of the CuInS2 seed NCs is crucial to allow the concentration of [ZnS] monomers to build up, thereby maximizing the anisotropic heteroepitaxial growth rates while minimizing the rates of competing processes (etching, cation exchange, alloying). Nevertheless, a mild etching still occurred, likely prior to the onset of heteroepitaxial overgrowth, shrinking the core size from 5.5 to ∼4 nm. The insights provided by this work open up new possibilities in designing multifunctional Cu-chalcogenide based colloidal heteronanocrystals. © 2018 American Chemical Society.},
note = {cited By 1},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Hendriks2018257,
title = {Integrated Transmission Electron and Single-Molecule Fluorescence Microscopy Correlates Reactivity with Ultrastructure in a Single Catalyst Particle},
author = { F.C. Hendriks and Sajjad Mohammadian and Z. Ristanović and S. Kalirai and F. Meirer and E.T.C. Vogt and P.C.A. Bruijnincx and Hans C. Gerritsen and B.M. Weckhuysen},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034657596&doi=10.1002%2fanie.201709723&partnerID=40&md5=5ec7400275144d61e7be3fb318585745},
doi = {10.1002/anie.201709723},
year  = {2018},
date = {2018-01-01},
journal = {Angewandte Chemie - International Edition},
volume = {57},
number = {1},
pages = {257-261},
abstract = {Establishing structure–activity relationships in complex, hierarchically structured nanomaterials, such as fluid catalytic cracking (FCC) catalysts, requires characterization with complementary, correlated analysis techniques. An integrated setup has been developed to perform transmission electron microscopy (TEM) and single-molecule fluorescence (SMF) microscopy on such nanostructured samples. Correlated structure–reactivity information was obtained for 100 nm thin, microtomed sections of a single FCC catalyst particle using this novel SMF-TEM high-resolution combination. High reactivity in a thiophene oligomerization probe reaction correlated well with TEM-derived zeolite locations, while matrix components, such as clay and amorphous binder material, were found not to display activity. Differences in fluorescence intensity were also observed within and between distinct zeolite aggregate domains, indicating that not all zeolite domains are equally active. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.},
note = {cited By 3},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Xia2018b,
title = {Size-Dependent Band-Gap and Molar Absorption Coefficients of Colloidal CuInS2 Quantum Dots},
author = { Cheng-Hui Xia and W. Wu and T. Yu and X. Xie and C.V. Oversteeg and Hans C. Gerritsen and Celso De Mello Donega},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052281980&doi=10.1021%2facsnano.8b03641&partnerID=40&md5=1cd5167c14bae03656197e6bb145296f},
doi = {10.1021/acsnano.8b03641},
year  = {2018},
date = {2018-01-01},
journal = {ACS Nano},
abstract = {The knowledge of the quantum dot (QD) concentration in a colloidal suspension and the quantitative understanding of the size-dependence of the band gap of QDs are of crucial importance from both applied and fundamental viewpoints. In this work, we investigate the size-dependence of the optical properties of nearly spherical wurtzite (wz) CuInS2 (CIS) QDs in the 2.7 to 6.1 nm diameter range (polydispersity ≤10%). The QDs are synthesized by partial Cu+ for In3+ cation exchange in template Cu2-xS NCs, which yields CIS QDs with very small composition variations (In/Cu= 0.91±0.11), regardless of their sizes. These well-defined QDs are used to investigate the size dependence of the band gap of wz CIS QDs. A sizing curve is also constructed for chalcopyrite CIS QDs by collecting and reanalyzing literature data. We observe that both sizing curves follow primarily a 1/d dependence. Moreover, the molar absorption coefficients and the absorption cross-section per CIS formula unit, both at 3.1 eV and at the band gap, are analyzed. The results demonstrate that the molar absorption coefficients of CIS QDs follow a power law at the first exciton transition energy (ϵE1)=5208 d^2.45), and scale with the QD volume at 3.1 eV. This latter observation implies that the absorption cross-section per unit cell at 3.1 eV is size-independent, and therefore can be estimated from bulk optical constants. These results also demonstrate that the molar absorption coefficients at 3.1 eV are more reliable for analytical purposes, since they are less sensitive to size and shape dispersion. © 2018 American Chemical Society.},
note = {cited By 0; Article in Press},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{van_hest_role_2018,
title = {The Role of a Phonon Bottleneck in Relaxation Processes for Ln-Doped NaYF4 Nanocrystals},
author = { Jacobine J. H. A. van Hest and Gerhard A. Blab and Hans C. Gerritsen and Celso de Mello Donega and Andries Meijerink},
url = {https://doi.org/10.1021/acs.jpcc.7b11171},
doi = {10.1021/acs.jpcc.7b11171},
issn = {1932-7447},
year  = {2018},
date = {2018-01-01},
urldate = {2018-09-11},
journal = {The Journal of Physical Chemistry C},
volume = {122},
number = {7},
pages = {3985--3993},
abstract = {The localized inner 4f shell transitions of lanthanide ions are largely independent of the local surroundings. The luminescence properties of Ln3+ ions doped into nanocrystals (NCs) are therefore similar to those in bulk crystals. Quantum size effects, responsible for the unique size-dependent luminescence of semiconductor NCs, are generally assumed not to influence the optical properties of Ln3+-doped insulator NCs. However, phonon confinement effects have been reported to hamper relaxation between closely spaced Stark levels in Ln3+-doped NCs. At cryogenic temperatures emission and excitation from higher Stark levels was observed for Ln3+ ions in NCs only and were explained by a cutoff in the acoustic phonon spectrum. Relaxation would be inhibited as no resonant low energy (long wavelength) acoustic phonon modes can exist in nanometer sized crystals, and this prevents relaxation by direct phonon emission between closely spaced Stark levels. This phenomenon is known as a phonon bottleneck. Here, we investigate the role of phonon confinement in Ln-doped NCs. High resolution emission spectra at temperatures down to 2.2 K are reported for various Ln3+ ions (Er3+, Yb3+, Eu3+) doped into monodisperse 10 nm NaYF4 NCs and compared with spectra for bulk (microcrystalline) material. Contrary to previous reports, we find no evidence for phonon bottleneck effects in the emission spectra. Emission from closely spaced higher Stark levels is observed only at high excitation powers and is explained by laser heating. The present results indicate that previously reported effects in NCs may not be caused by phonon confinement.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{doi:10.1021/acs.jpcc.7b06549,
title = {Probing the Influence of Disorder on Lanthanide Luminescence Using Eu-Doped LaPO4 Nanoparticles},
author = { Jacobine J.H.A. van Hest and Gerhard A. Blab and Hans C. Gerritsen and Celso de Mello-Donega and Andries Meijerink},
url = {http://dx.doi.org/10.1021/acs.jpcc.7b06549},
doi = {10.1021/acs.jpcc.7b06549},
year  = {2017},
date = {2017-01-01},
journal = {The Journal of Physical Chemistry C},
volume = {121},
number = {35},
pages = {19373-19382},
abstract = {Lanthanide-doped nanocrystals (NCs) differ from their bulk counterparts due to their large surface to volume ratio. It is generally assumed that the optical properties are not affected by size effects as electronic transitions occur within the well-shielded 4f shell of the lanthanide dopant ions. However, defects and disorder in the surface layer can affect the luminescence properties. Trivalent europium is a suitable ion to investigate the subtle influence of the surface, because of its characteristic luminescence and high sensitivity to the local environment. Here, we investigate the influence of disorder in NCs on the optical properties of lanthanide dopants by studying the inhomogeneous linewidth, emission intensity ratios, and luminescence decay curves for LaPO4:Eu3+ samples of different sizes (4 nm to bulk) and core–shell configurations (core, core–isocrystalline shell, and core–silica shell). We show that the emission linewidths increase strongly for NCs. The ratio of the intensities of the forced electric dipole (ED) and magnetic dipole (MD) transitions, a measure for the local symmetry distortion around Eu3+ ions, is higher for samples with a large fraction of Eu3+ ions close to the surface. Finally, we present luminescence decay curves revealing an increased nonradiative decay rate for Eu3+ in NCs. The effects are strongest in core and core–silica shell NCs and can be reduced by growth of an isocrystalline LaPO4 shell. The present systematic study provides quantitative insight into the role of surface disorder on the optical properties of lanthanide-doped NCs. These insights are important in emerging applications of lanthanide-doped nanocrystals.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Xia20174940,
title = {Highly Luminescent Water-Dispersible NIR-Emitting Wurtzite CuInS2/ZnS Core/Shell Colloidal Quantum Dots},
author = { Cheng-Hui Xia and Johannes D. Meeldijk and Hans C. Gerritsen and Celso de Mello-Donega},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020755702&doi=10.1021%2facs.chemmater.7b01258&partnerID=40&md5=e2ad969aafe4216675cf983c833eb6b0},
doi = {10.1021/acs.chemmater.7b01258},
year  = {2017},
date = {2017-01-01},
journal = {Chemistry of Materials},
volume = {29},
number = {11},
pages = {4940-4951},
abstract = {Copper indium sulfide (CIS) quantum dots (QDs) are attractive as labels for biomedical imaging, since they have large absorption coefficients across a broad spectral range, size- and composition-tunable photoluminescence from the visible to the near-infrared, and low toxicity. However, the application of NIR-emitting CIS QDs is still hindered by large size and shape dispersions and low photoluminescence quantum yields (PLQYs). In this work, we develop an efficient pathway to synthesize highly luminescent NIR-emitting wurtzite CIS/ZnS QDs, starting from template Cu2-xS nanocrystals (NCs), which are converted by topotactic partial Cu+ for In3+ exchange into CIS NCs. These NCs are subsequently used as cores for the overgrowth of ZnS shells (≤1 nm thick). The CIS/ZnS core/shell QDs exhibit PL tunability from the first to the second NIR window (750-1100 nm), with PLQYs ranging from 75% (at 820 nm) to 25% (at 1050 nm), and can be readily transferred to water upon exchange of the native ligands for mercaptoundecanoic acid. The resulting water-dispersible CIS/ZnS QDs possess good colloidal stability over at least 6 months and PLQYs ranging from 39% (at 820 nm) to 6% (at 1050 nm). These PLQYs are superior to those of commonly available water-soluble NIR-fluorophores (dyes and QDs), making the hydrophilic CIS/ZnS QDs developed in this work promising candidates for further application as NIR emitters in bioimaging. The hydrophobic CIS/ZnS QDs obtained immediately after the ZnS shelling are also attractive as fluorophores in luminescent solar concentrators. © 2017 American Chemical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Thomas201724,
title = {Studying skin tumourigenesis and progression in immunocompetent hairless SKH1-hr mice using chronic 7,12-dimethylbenz(a)anthracene topical applications to develop a useful experimental skin cancer model},
author = {Giju Thomas and Bastiaan Tuk and Ji Ying Song and Hoa H. Truong and Hans C. Gerritsen and Frank R. de Gruijl and Henricus J.C.M. Sterenborg},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014446283&doi=10.1177%2f0023677216637305&partnerID=40&md5=86fdf0245e203bd2db167d9b507f5661},
doi = {10.1177/0023677216637305},
year  = {2017},
date = {2017-01-01},
journal = {Laboratory Animals},
volume = {51},
number = {1},
pages = {24-35},
abstract = {Previous studies have established that 7,12-dimethylbenz(a)anthracene (DMBA) can initiate skin tumourigenesis in conventional furred mouse models by acting on hair follicle stem cells. However, further cancer progression depends on repeated applications of tumour promoter agents. This study evaluated the timeline involved in skin tumourigenesis and progression in immunocompetent hairless SKH1-hr mice with dysfunctional hair follicles using only DMBA with no additional tumour promoter agents. The results showed that topical application of 30 μg (117 nmol) of DMBA over the back and flank regions of the mouse once a week and 15 μg (58.5 nmol) twice a week produced skin tumours after 7–8 weeks. However, by week 14 a heavy benign tumour load required the mice to be euthanized. Lowering the DMBA dose to 15 μg (58.5 nmol) once a week produced tumours more slowly and allowed the mice to be studied for a longer period to week 23. This lowdose DMBA regimen yielded a high percentage of malignant tumours (58.8%) after 23 weekly applications. Additionally DMBA-treated skin showed an increase in mean epidermal thickness in comparison to untreated and acetone-treated skin. Despite the aberrant hair follicles in SKH1-hr mice, this chemically driven skin cancer model in hairless mice can serve as a suitable alternative to the ultraviolet-induced skin cancer models and can be reliably replicated as demonstrated by both the pilot and main experiments. © The Author(s) 2016.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{van_hest_incorporation_2016,
title = {Incorporation of Ln-Doped LaPO4 Nanocrystals as Luminescent Markers in Silica Nanoparticles},
author = {Jacobine J.H.A. van Hest and Gerhard A. Blab and Hans C. Gerritsen and Celso de Mello-Donega and Andries Meijerink},
url = {http://nanoscalereslett.springeropen.com/articles/10.1186/s11671-016-1465-y},
doi = {10.1186/s11671-016-1465-y},
issn = {1931-7573, 1556-276X},
year  = {2016},
date = {2016-01-01},
urldate = {2016-07-11},
journal = {Nanoscale Research Letters},
volume = {11},
number = {1},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@inbook{deJonge2015,
title = {Advances in Imaging and Electron Physics (contr.)},
author = {Niels de Jonge and Gerhard A. Blab and Matthia A. Karreman and Alexandra V. Agronskaia and Hans C. Gerritsen},
editor = {Peter W. Hawkes},
doi = {10.1016/bs.aiep.2015.02.004},
isbn = {978-0-12-802380-8},
year  = {2015},
date = {2015-05-18},
volume = {190},
pages = {1--102},
publisher = {978-0-12-802380-8 },
address = {225 Wyman Street, Waltham, MA 02451, USA 525 B Street, Suite 1800, San Diego, CA 92101-4495, USA 125 London Wall, London, EC2Y 5AS, UK The Boulevard, Langford Lane, Kidlington, Oxford OX5 1GB, UK},
chapter = {1},
series = {Advances in Imaging and Electron Physics},
abstract = {This chapter contains the extended abstracts of the second conference on in situ and correlative electron microscopy (CISCEM 2014), held October 14–15, 2014, in Saarbrücken, Germany. The conference was housed at the INM-Leibniz Institute for New Materials. The aim of the conference was to bring together an interdisciplinary group of scientists from the fields of biology, materials science, chemistry, and physics to discuss future directions of electron microscopy research. The topics of the different sessions were correlative and in situ electron microscopy in biology, in situ observations of biomineralization processes, designing in situ experiments, high-temperature and other experiments, and in situ transmission electron microscopy of catalytic nanoparticles. A corporate session was also held.},
type = {Academic Press},
keywords = {Correlated Microscopy, Electron Microscopy, FIB/SEM, Integrated Microscopy, Light Microscopy, SEM, TEM},
pubstate = {published},
tppubtype = {inbook}
}
@article{Zuckermann2015,
title = {Motor properties from persistence: a linear molecular walker lacking spatial and temporal asymmetry},
author = {Martin J. Zuckermann and Christopher N. Angstmann and Regina Schmitt and Gerhard A. Blab and Elizabeth H.C. Bromley and Nancy R. Forde and Heiner Linke and Paul M.G. Curmi},
url = {http://iopscience.iop.org/1367-2630/17/5/055017/},
doi = {10.1088/1367-2630/17/5/055017},
year  = {2015},
date = {2015-05-05},
journal = {New Journal of Phyiscs},
volume = {17},
pages = {055017},
abstract = {The stepping direction of linear molecular motors is usually defined by a spatial asymmetry of the motor, its track, or both. Here we present a model for a molecular walker that undergoes biased directional motion along a symmetric track in the presence of a temporally symmetric chemical cycle. Instead of using asymmetry, directionality is achieved by persistence. At small load force the walker can take on average thousands of steps in a given direction until it stochastically reverses direction. We discuss a specific experimental implementation of a synthetic motor based on this design and find, using Langevin and Monte Carlo simulations, that a realistic walker can work against load forces on the order of picoNewtons with an efficiency of ~18%, comparable to that of kinesin. In principle, the walker can be turned into a permanent motor by externally monitoring the walker's momentary direction of motion, and using feedback to adjust the direction of a load force. We calculate the thermodynamic cost of using feedback to enhance motor performance in terms of the Shannon entropy, and find that it reduces the efficiency of a realistic motor only marginally. We discuss the implications for natural protein motor performance in the context of the strong performance of this design based only on a thermal ratchet.},
keywords = {Linear Motors, Thermodynamics},
pubstate = {published},
tppubtype = {article}
}
@article{vanImhof2015,
title = {Jammed elastic shells – a 3D experimental soft frictionless granular system },
author = {Jissy Jose and Gerhard A. Blab and Alfons van Blaaderen and Arnout Imhof},
url = {http://pubs.rsc.org/en/content/articlelanding/2015/sm/c4sm02098g},
doi = {10.1039/C4SM02098G },
year  = {2015},
date = {2015-03-07},
journal = {Soft Matter},
volume = {11},
number = {9},
pages = {1800-1813},
abstract = {We present a new experimental system of monodisperse, soft, frictionless, fluorescent labeled elastic shells for the characterization of structure, universal scaling laws and force networks in 3D jammed matter. The elastic shells in a jammed packing are deformed in such a way that at each contact one of the shells buckles with a dimple and the other remain spherical, closely resembling overlapping spheres. Using confocal microscopy, we obtained 3D stacks of images of shells at different volume fractions which were subsequently processed in ImageJ software to find their coordinates. The determination of 3D coordinates involved three steps: locating the edges of shells in all 2D slices, analyzing their shape and subsequently finding their 2D coordinates, and finally determining their 3D centers by grouping the corresponding 2D coordinates. From this analysis routine we obtained particle coordinates with sub-pixel accuracy. In a contact pair we also identified the shell that underwent buckling forming a dimple by analyzing the intensity profile of a line that connects the centers of particle pairs. The amorphous structure of the packing was analyzed as a function of distance to the jamming threshold by investigating the radial distribution function, bond order parameters, contact numbers and the number of dimples per particle (buckling number), which is a unique property of this system. We find that the power law scaling of the contact number with excess volume fraction deviated from theoretical and computer simulation predictions. In addition, the buckling number also showed a similar scaling as that of the contact number with distance to the jamming transition.},
keywords = {Colloids, Elastic Shells},
pubstate = {published},
tppubtype = {article}
}
@article{PIP:PIP2702,
title = {3D-printed external light trap for solar cells},
author = {Lourens van Dijk and Ulrich W. Paetzold and Gerhard A. Blab and Ruud E.I. Schropp and Marcel di Vece},
url = {http://dx.doi.org/10.1002/pip.2702},
doi = {10.1002/pip.2702},
issn = {1099-159X},
year  = {2015},
date = {2015-01-01},
journal = {Progress in Photovoltaics: Research and Applications},
pages = {n/a--n/a},
abstract = {We present a universally applicable 3D-printed external light trap for enhanced absorption in solar cells. The macroscopic external light trap is placed at the sun-facing surface of the solar cell and retro-reflects the light that would otherwise escape. The light trap consists of a reflective parabolic concentrator placed on top of a reflective cage. Upon placement of the light trap, an improvement of 15% of both the photocurrent and the power conversion efficiency in a thin-film nanocrystalline silicon (nc-Si:H) solar cell is measured. The trapped light traverses the solar cell several times within the reflective cage thereby increasing the total absorption in the cell. Consequently, the trap reduces optical losses and enhances the absorption over the entire spectrum. The components of the light trap are 3D printed and made of smoothened, silver-coated thermoplastic. In contrast to conventional light trapping methods, external light trapping leaves the material quality and the electrical properties of the solar cell unaffected. To explain the theoretical operation of the external light trap, we introduce a model that predicts the absorption enhancement in the solar cell by the external light trap. The corresponding calculated path length enhancement shows good agreement with the empirically derived value from the opto-electrical data of the solar cell. Moreover, we analyze the influence of the angle of incidence on the parasitic absorptance to obtain full understanding of the trap performance.Copyright © 2015 © 2015 The Authors. Progress in Photovoltaics: Research and Applications published by John Wiley & Sons Ltd.},
note = {pip.2702},
keywords = {3D printing, anti-reflection, compound parabolic concentrator (CPC), external light trapping, thin-film solar cells},
pubstate = {published},
tppubtype = {article}
}
@article{Thomas2014,
title = {Advances and challenges in label-free nonlinear optical imaging using two-photon excitation fluorescence and second harmonic generation for cancer research},
author = { Giju Thomas and Johan van Voskuilen and Hans C. Gerritsen and Henricus J.C.M. Sterenborg},
doi = {10.1016/j.jphotobiol.2014.08.02510.1016},
year  = {2014},
date = {2014-12-01},
journal = {J. Photochem. Photobiol. B, Biol.},
volume = {141},
pages = {128--138},
abstract = {Nonlinear optical imaging (NLOI) has emerged to be a promising tool for bio-medical imaging in recent times. Among the various applications of NLOI, its utility is the most significant in the field of pre-clinical and clinical cancer research. This review begins by briefly covering the core principles involved in NLOI, such as two-photon excitation fluorescence (TPEF) and second harmonic generation (SHG). Subsequently, there is a short description on the various cellular components that contribute to endogenous optical fluorescence. Later on the review deals with its main theme--the challenges faced during label-free NLO imaging in translational cancer research. While this review addresses the accomplishment of various label-free NLOI based studies in cancer diagnostics, it also touches upon the limitations of the mentioned studies. In addition, areas in cancer research that need to be further investigated by label-free NLOI are discussed in a latter segment. The review eventually concludes on the note that label-free NLOI has and will continue to contribute richly in translational cancer research, to eventually provide a very reliable, yet minimally invasive cancer diagnostic tool for the patient.},
note = {[DOI:hrefhttp://dx.doi.org/10.1016/j.jphotobiol.2014.08.02510.1016/j.jphotobiol.2014.08.025] [PubMed:hrefhttp://www.ncbi.nlm.nih.gov/pubmed/2546366025463660]},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{pmid25319484,
title = {In vivo nonlinear optical imaging to monitor early microscopic changes in a murine cutaneous squamous cell carcinoma model},
author = {Giju Thomas and Johan van Voskuilen and Hoa H. Truong and Hans C. Gerritsen and Henricus J.C.M. Sterenborg},
doi = {10.1002/jbio.201400074},
year  = {2014},
date = {2014-10-15},
journal = {J Biophotonics},
volume = {9999},
number = {9999},
abstract = {Early detection of cutaneous squamous cell carcinoma (cSCC) can enable timely therapeutic and preventive interventions for patients. In this study, in vivo nonlinear optical imaging (NLOI) based on two-photon excitation fluorescence (TPEF) and second harmonic generation (SHG), was used to non-invasively detect microscopic changes occurring in murine skin treated topically with 7,12-dimethylbenz(a)anthracene (DMBA). The optical microscopic findings and the measured TPEF-SHG index show that NLOI was able to clearly detect early cytostructural changes in DMBA treated skin that appeared clinically normal. This suggests that in vivo NLOI could be a non-invasive tool to monitor early signs of cSCC. In vivo axial NLOI scans of normal murine skin (upper left), murine skin with preclinical hyperplasia (upper right), early clinical murine skin lesion (lower left) and late or advanced murine skin lesion (lower right).},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{pmid23401419,
title = {Estimating the risk of squamous cell cancer induction in skin following nonlinear optical imaging},
author = { Giju Thomas and Oleg Nadiarnykh and Johan van Voskuilen and Christopher L. Hoy and Hans C. Gerritsen and Henricus J.C.M. Sterenborg},
year  = {2014},
date = {2014-07-01},
journal = {J Biophotonics},
volume = {7},
number = {7},
pages = {492--505},
abstract = {High power femto-second (fs) laser pulses used for in-vivo nonlinear optical (NLO) imaging can form cyclobutane pyrimidine dimers (CPD) in DNA, which may lead to carcinogenesis via subsequent mutations. Since UV radiation from routine sun exposure is the primary source of CPD lesions, we evaluated the risk of CPD-related squamous cell carcinoma (SCC) in human skin due to NLO imaging relative to that from sun exposure. We developed a unique cancer risk model expanding previously published estimation of risk from exposure to continuous wave (CW) laser. This new model showed that the increase in CPD-related SCC in skin from NLO imaging is negligible above that due to regular sun exposure.},
note = {[DOI:hrefhttp://dx.doi.org/10.1002/jbio.20120020710.1002/jbio.201200207] [PubMed:hrefhttp://www.ncbi.nlm.nih.gov/pubmed/2340141923401419]},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Revalee2014705,
title = {Tethered particle motion reveals that LacI·DNA loops coexist with a competitor-resistant but apparently unlooped conformation},
author = { Joel D. Revalee and Gerhard A. Blab and Henry D. Wilson and Jason D. Kahn and Jens Christian Meiners},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84893515191&partnerID=40&md5=b469b5118033e09f75eb18a2f5dee398},
doi = {10.1016/j.bpj.2013.12.024},
year  = {2014},
date = {2014-02-04},
journal = {Biophysical Journal},
volume = {106},
number = {3},
pages = {705-715},
abstract = {The lac repressor protein (LacI) efficiently represses transcription of the lac operon in Escherichia coli by binding to two distant operator sites on the bacterial DNA and causing the intervening DNA to form a loop. We employed single-molecule tethered particle motion to observe LacI-mediated loop formation and breakdown in DNA constructs that incorporate optimized operator binding sites and intrinsic curvature favorable to loop formation. Previous bulk competition assays indirectly measured the loop lifetimes in these optimized DNA constructs as being on the order of days; however, we measured these same lifetimes to be on the order of minutes for both looped and unlooped states. In a range of single-molecule DNA competition experiments, we found that the resistance of the LacI-DNA complex to competitive binding is a function of both the operator strength and the interoperator sequence. To explain these findings, we present what we believe to be a new kinetic model of loop formation and DNA competition. In this proposed new model, we hypothesize a new unlooped state in which the unbound DNA-binding domain of the LacI protein interacts nonspecifically with nonoperator DNA adjacent to the operator site at which the second LacI DNA-binding domain is bound. © 2014 Biophysical Society.},
note = {cited By 1},
keywords = {DNA, DNA geometry, DNA loops, Force Spectroscopy, Lac Repressor},
pubstate = {published},
tppubtype = {article}
}
@article{2050-6120-2-3-035001,
title = {Phasor based analysis of FRET images recorded using spectrally resolved lifetime imaging},
author = {Farzad Fereidouni and Gerhard A. Blab and Hans C. Gerritsen},
url = {http://stacks.iop.org/2050-6120/2/i=3/a=035001},
year  = {2014},
date = {2014-01-01},
journal = {Methods and Applications in Fluorescence},
volume = {2},
number = {3},
pages = {035001},
abstract = {The combined analysis of spectral and lifetime images has the potential to provide more accurate and more detailed information about Förster resonance energy transfer (FRET). We have developed a novel FRET analysis method to analyze images recorded by multispectral lifetime imaging. The new method is based on a phasor approach and facilitates the simultaneous analysis of decay kinetics of donor and acceptor molecules. The method is applicable to both molecules that exhibit a mono-exponential decay and a bi-exponential decay. As an example we show the possibility of extracting the energy transfer efficiency and the fraction of interacting molecules even in the presence of non-interacting molecules. The reliability of the method is investigated by comparing it with conventional FRET-FLIM analyses. We show that, with the same number of detected photons, the spectrally resolved phasor approach provides higher accuracy than other analysis methods; the confidence interval is improved and the FRET efficiency is closer to the real value.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Knaus2013,
title = {Label-free fluorescence microscopy in fungi},
author = {Helene Knaus and Gerhard A. Blab and G. Jerre van Veluw and Hans C. Gerritsen and Han A.B. Wösten},
url = {http://www.sciencedirect.com/science/article/pii/S1749461313000304},
doi = {http://dx.doi.org/10.1016/j.fbr.2013.05.003},
issn = {1749-4613},
year  = {2013},
date = {2013-01-01},
journal = {Fungal Biology Reviews},
number = {0},
pages = {-},
abstract = {Abstract Label-free fluorescence microscopy detects fluorescence originating from endogenous fluorophores, such as NAD(P)H, melanin and flavins. The emitted fluorescence (spectrum, lifetime and polarization) is characteristic for the molecule and its environment. In most cases, a specimen contains multiple autofluorescent molecules contributing to the overall fluorescence. Methods have been developed to break down the fluorescence into the contribution of its individual components. As a result, label-free microscopy can map biochemical properties of fluorophores spatially and over time at the level of the organism, tissue and cells. This is of interest for fungal cell biology and development. Moreover, it can be used in biotechnological applications to monitor the metabolic state within a bioreactor or to monitor the formation of secondary metabolites. Combining morphological and biochemical properties can also lead to new developments in fungal taxonomy, biomedical diagnostics, as well as the screening of fungal products such as mushrooms.},
note = {in press},
keywords = {Metabolism},
pubstate = {published},
tppubtype = {article}
}
@article{Karreman20133846,
title = {Probing the different life stages of a fluid catalytic cracking particle with integrated laser and electron microscopy},
author = {Matthia A. Karreman and Inge L.C. Buurmans and Alexandra V. Agronskaia and John W. Geus and Hans C. Gerritsen and Bert M. Weckhuysen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84874956221&partnerID=40&md5=72b6f2ef1b89aa61bc7980e511ff7982},
year  = {2013},
date = {2013-01-01},
journal = {Chemistry - A European Journal},
volume = {19},
number = {12},
pages = {3846-3859},
abstract = {While cycling through a fluid catalytic cracking (FCC) unit, the structure and performance of FCC catalyst particles are severely affected. In this study, we set out to characterize the damage to commercial equilibrium catalyst particles, further denoted as ECat samples, and map the different pathways involved in their deactivation in a practical unit. The degradation was studied on a structural and a functional level. Transmission electron microscopy (TEM) of ECat samples revealed several structural features; including zeolite crystals that were partly or fully severed, mesoporous, macroporous, and/or amorphous. These defects were then correlated to structural features observed in FCC particles that were treated with different levels of hydrothermal deactivation. This allowed us not only to identify which features observed in ECat samples were a result of hydrothermal deactivation, but also to determine the severity of treatments resulting in these defects. For functional characterization of the ECat sample, the Brønsted acidity within individual FCC particles was studied by a selective fluorescent probe reaction with 4-fluorostyrene. Integrated laser and electron microscopy (iLEM) allowed correlating this Brønsted acidity to structural features by combining a fluorescence and a transmission electron microscope in a single set-up. Together, these analyses allowed us to postulate a plausible model for the degradation of zeolite crystals in FCC particles in the ECat sample. Furthermore, the distribution of the various deactivation processes within particles of different ages was studied. A rim of completely deactivated zeolites surrounding each particle in the ECat sample was identified by using iLEM. These zeolites, which were never observed in fresh or steam-deactivated samples, contained clots of dense structures. The structures are proposed to be carbonaceous deposits formed during the cracking process, and seem resistant towards burning off during catalyst regeneration. Exposing the cracks: Several processes in an industrial fluid catalytic cracking (FCC) unit lead to deactivation of FCC particles. A structural and functional analysis of hydrothermally deactivated FCC particles and particles from a commercial equilibrium catalyst particle (ECat) sample was performed. A model is postulated for the degradation of the zeolite component. Inter- and intraparticle distributions of defects were mapped, resulting in the identification of a rim of fully deactivated zeolites (see figure). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.},
note = {cited By (since 1996) 0},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Faas2013283,
title = {Localization of fluorescently labeled structures in frozen-hydrated samples using integrated light electron microscopy},
author = {Frank G.A. Faas and Montserrat Bárcena and Alexandra V. Agronskaia and Hans C. Gerritsen and Katarzyna B. Moscicka and Christoph A. Diebolder and Linda F. van Driel and Ronald W.A.L. Limpens and Erik Bos and Raimond B.G. Ravelli and Roman I. Koning and Abraham J. Koster},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84874000908&partnerID=40&md5=07de417233471010ab2ddb151974b31e},
year  = {2013},
date = {2013-01-01},
journal = {Journal of Structural Biology},
volume = {181},
number = {3},
pages = {283-290},
abstract = {Correlative light and electron microscopy is an increasingly popular technique to study complex biological systems at various levels of resolution. Fluorescence microscopy can be employed to scan large areas to localize regions of interest which are then analyzed by electron microscopy to obtain morphological and structural information from a selected field of view at nm-scale resolution. Previously, an integrated approach to room temperature correlative microscopy was described. Combined use of light and electron microscopy within one instrument greatly simplifies sample handling, avoids cumbersome experimental overheads, simplifies navigation between the two modalities, and improves the success rate of image correlation. Here, an integrated approach for correlative microscopy under cryogenic conditions is presented. Its advantages over the room temperature approach include safeguarding the native hydrated state of the biological specimen, preservation of the fluorescence signal without risk of quenching due to heavy atom stains, and reduced photo bleaching. The potential of cryo integrated light and electron microscopy is demonstrated for the detection of viable bacteria, the study of in vitro polymerized microtubules, the localization of mitochondria in mouse embryonic fibroblasts, and for a search into virus-induced intracellular membrane modifications within mammalian cells. © 2012 Elsevier Inc.},
note = {cited By (since 1996) 0},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{vanSpronsen2013485,
title = {TRAK/Milton Motor-Adaptor Proteins Steer Mitochondrial Trafficking to Axons and Dendrites},
author = {Myrrhe van Spronsen and Marina Mikhaylova and Joanna Lipka and Max A. Schlager and Dave J. van den Heuvel and Marijn Kuijpers and Phebe S. Wulf and Nanda Keijzer and Jeroen A.A. Demmers and Lukas C. Kapitein and Dick Jaarsma and Hans C. Gerritsen and Anna S. Akhmanova and Casper C. Hoogenraad},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84873279659&partnerID=40&md5=53f917e82bb41c31d7cd3eaf1ebdb2b4},
year  = {2013},
date = {2013-01-01},
journal = {Neuron},
volume = {77},
number = {3},
pages = {485-502},
abstract = {In neurons, the distinct molecular composition of axons and dendrites is established through polarized targeting mechanisms, but it is currently unclear how nonpolarized cargoes, such as mitochondria, become uniformly distributed over these specialized neuronal compartments. Here, we show that TRAK family adaptor proteins, TRAK1 and TRAK2, which link mitochondria to microtubule-based motors, are required for axonal and dendritic mitochondrial motility and utilize different transport machineries to steer mitochondria into axons and dendrites. TRAK1 binds to both kinesin-1 and dynein/dynactin, is prominently localized in axons, and is needed for normal axon outgrowth, whereas TRAK2 predominantly interacts with dynein/dynactin, is more abundantly present in dendrites, and is required for dendritic development. These functional differences follow from their distinct conformations: TRAK2 preferentially adopts a head-to-tail interaction, which interferes with kinesin-1 binding and axonal transport. Our study demonstrates how the molecular interplay between bidirectional adaptor proteins and distinct microtubule-based motors drives polarized mitochondrial transport. van Spronsen et al. show that mitochondria utilize different machineries to steer their transport into axons and dendrites. The molecular interplay between mitochondrial adaptor protein family TRAK/Milton and distinct microtubule-based motors drives polarized mitochondrial transport. © 2013 Elsevier Inc.},
note = {cited By (since 1996) 0},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Knaus20136345,
title = {Monitoring the metabolic state of fungal hyphae and the presence of melanin by nonlinear spectral imaging},
author = {Helene Knaus and Gerhard A. Blab and Alexandra V. Agronskaia and Dave J. van den Heuvel and Hans C. Gerritsen and Han A.B. Wösten},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84885037949&partnerID=40&md5=d7640036730e5e1be25a63231c0c47ec},
doi = {10.1128/AEM.02291-13},
year  = {2013},
date = {2013-01-01},
journal = {Applied and Environmental Microbiology},
volume = {79},
number = {20},
pages = {6345-6350},
note = {cited By 2},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Fereidouni2013,
title = {Blind unmixing of spectrally resolved lifetime images},
author = {Farzad Fereidouni and Gerhard A. Blab and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84892490015&partnerID=40&md5=2a47200af50b1f0806307feacaca9673},
doi = {10.1117/1.JBO.18.8.086006},
year  = {2013},
date = {2013-01-01},
journal = {Journal of Biomedical Optics},
volume = {18},
number = {8},
note = {cited By 6},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{pmid23214185,
title = {Carcinogenic damage to deoxyribonucleic acid is induced by near-infrared laser pulses in multiphoton microscopy via combination of two- and three-photon absorption},
author = {Oleg Nadiarnykh and Giju Thomas and Johan van Voskuilen and Henricus J.C.M. Sterenborg and Hans C. Gerritsen},
year  = {2012},
date = {2012-11-01},
journal = {J Biomed Opt},
volume = {17},
number = {11},
pages = {116024},
abstract = {Nonlinear optical imaging modalities (multiphoton excited fluorescence, second and third harmonic generation) applied in vivo are increasingly promising for clinical diagnostics and the monitoring of cancer and other disorders, as they can probe tissue with high diffraction-limited resolution at near-infrared (IR) wavelengths. However, high peak intensity of femtosecond laser pulses required for two-photon processes causes formation of cyclobutane-pyrimidine-dimers (CPDs) in cellular deoxyribonucleic acid (DNA) similar to damage from exposure to solar ultraviolet (UV) light. Inaccurate repair of subsequent mutations increases the risk of carcinogenesis. In this study, we investigate CPD damage that results in Chinese hamster ovary cells in vitro from imaging them with two-photon excited autofluorescence. The CPD levels are quantified by immunofluorescent staining. We further evaluate the extent of CPD damage with respect to varied wavelength, pulse width at focal plane, and pixel dwell time as compared with more pronounced damage from UV sources. While CPD damage has been expected to result from three-photon absorption, our results reveal that CPDs are induced by competing twoand three-photon absorption processes, where the former accesses UVA absorption band. This finding is independently confirmed by nonlinear dependencies of damage on laser power, wavelength, and pulse width.},
note = {[PubMed:hrefhttp://www.ncbi.nlm.nih.gov/pubmed/2321418523214185]},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Gitz20121873,
title = {Improved platelet survival after cold storage by prevention of glycoprotein Ibα clustering in lipid rafts},
author = {Eelo Gitz and Cornelis A. Koekman and Dave J. van den Heuvel and Hans Deckmyn and Jan Willem N. Akkerman and Hans C. Gerritsen and Rolf T. Urbanus},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84869885949&partnerID=40&md5=446f25fb0e7209b3093c1006feeb7767},
year  = {2012},
date = {2012-01-01},
journal = {Haematologica},
volume = {97},
number = {12},
pages = {1873-1881},
abstract = {Background Storing platelets for transfusion at room temperature increases the risk of microbial infection and decreases platelet functionality, leading to out-date discard rates of up to 20%. Cold storage may be a better alternative, but this treatment leads to rapid platelet clearance after transfusion, initiated by changes in glycoprotein Ibα, the receptor for von Willebrand factor. Design and Methods We examined the change in glycoprotein Ibα distribution using Förster resonance energy transfer by time-gated fluorescence lifetime imaging microscopy. Results Cold storage induced deglycosylation of glycoprotein Ibα ectodomain, exposing N-acetyl-D-glucosamine residues, which sequestered with GM1 gangliosides in lipid rafts. Raft-associated glycoprotein Ibα formed clusters upon binding of 14-3-3ζ adaptor proteins to its cytoplasmic tail, a process accompanied by mitochondrial injury and phosphatidyl serine exposure. Cold storage left glycoprotein Ibα surface expression unchanged and although glycoprotein V decreased, the fall did not affect glycoprotein Ibα clustering. Prevention of glycoprotein Ibα clustering by blockade of deglycosylation and 14-3-3ζ translocation increased the survival of cold-stored platelets to above the levels of platelets stored at room temperature without compromising hemostatic functions. Conclusions We conclude that glycoprotein Ibα translocates to lipid rafts upon cold-induced deglycosylation and forms clusters by associating with 14-3-3ζ. Interference with these steps provides a means to enable cold storage of platelet concentrates in the near future. © 2012 Ferrata Storti Foundation.},
note = {cited By (since 1996) 1},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Antonello20122428,
title = {Semidefinite programming for model-based sensorless adaptive optics},
author = {Jacopo Antonello and Michel H.G. Verhaegen and Rufus Fraanje and Tim van Werkhoven and Hans C. Gerritsen and Christoph U. Keller},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84869786716&partnerID=40&md5=202137cf58ed5b14c167285f48295edc},
year  = {2012},
date = {2012-01-01},
journal = {Journal of the Optical Society of America A: Optics and Image Science, and Vision},
volume = {29},
number = {11},
pages = {2428-2438},
abstract = {Wavefront sensorless adaptive optics methodologies are widely considered in scanning fluorescence microscopy where direct wavefront sensing is challenging. In these methodologies, aberration correction is performed by sequentially changing the settings of the adaptive element until a predetermined image quality metric is optimized. An efficient aberration correction can be achieved by modeling the image quality metric with a quadratic polynomial. We propose a new method to compute the parameters of the polynomial from experimental data. This method guarantees that the quadratic form in the polynomial is semidefinite, resulting in a more robust computation of the parameters with respect to existing methods. In addition, we propose an algorithm to perform aberration correction requiring a minimum of N + 1 measurements, where N is the number of considered aberration modes. This algorithm is based on a closed-form expression for the exact optimization of the quadratic polynomial. Our arguments are corroborated by experimental validation in a laboratory environment. © 2012 Optical Society of America.},
note = {cited By (since 1996) 0},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Karreman2012382,
title = {Optimizing immuno-labeling for correlative fluorescence and electron microscopy on a single specimen},
author = {Matthia A. Karreman and Alexandra V. Agronskaia and Elly G. van Donselaar and Karin Vocking and Farzad Fereidouni and Bruno M. Humbel and Cornelis T. Verrips and Ariel J. Verkleij and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84867908573&partnerID=40&md5=b6914e9a5caa2dc078389ca3daf42596},
year  = {2012},
date = {2012-01-01},
journal = {Journal of Structural Biology},
volume = {180},
number = {2},
pages = {382-386},
abstract = {Correlative fluorescence and electron microscopy has become an indispensible tool for research in cell biology. The integrated Laser and Electron Microscope (iLEM) combines a Fluorescence Microscope (FM) and a Transmission Electron Microscope (TEM) within one set-up. This unique imaging tool allows for rapid identification of a region of interest with the FM, and subsequent high resolution TEM imaging of this area. Sample preparation is one of the major challenges in correlative microscopy of a single specimen; it needs to be apt for both FM and TEM imaging. For iLEM, the performance of the fluorescent probe should not be impaired by the vacuum of the TEM. In this technical note, we have compared the fluorescence intensity of six fluorescent probes in a dry, oxygen free environment relative to their performance in water. We demonstrate that the intensity of some fluorophores is strongly influenced by its surroundings, which should be taken into account in the design of the experiment. Furthermore, a freeze-substitution and Lowicryl resin embedding protocol is described that yields excellent membrane contrast in the TEM but prevents quenching of the fluorescent immuno-labeling. The embedding protocol results in a single specimen preparation procedure that performs well in both FM and TEM. Such procedures are not only essential for the iLEM, but also of great value to other correlative microscopy approaches. © 2012 Elsevier Inc.},
note = {cited By (since 1996) 1},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Nadiarnykh2012,
title = {Carcinogenic damage to deoxyribonucleic acid is induced by near-infrared laser pulses in multiphoton microscopy via combination of two- and three-photon absorption},
author = {Oleg Nadiarnykh and GijuThomas and Johan van Voskuilen and Henricus J.C.M. Sterenborg and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84870600800&partnerID=40&md5=f65f5c42391abae69f91aa4b7a8939b8},
year  = {2012},
date = {2012-01-01},
journal = {Journal of Biomedical Optics},
volume = {17},
number = {11},
abstract = {Nonlinear optical imaging modalities (multiphoton excited fluorescence, second and third harmonic generation) applied in vivo are increasingly promising for clinical diagnostics and the monitoring of cancer and other disorders, as they can probe tissue with high diffraction-limited resolution at near-infrared (IR) wavelengths. However, high peak intensity of femtosecond laser pulses required for two-photon processes causes formation of cyclobutane-pyrimidine- dimers (CPDs) in cellular deoxyribonucleic acid (DNA) similar to damage from exposure to solar ultraviolet (UV) light. Inaccurate repair of subsequent mutations increases the risk of carcinogenesis. In this study, we investigate CPD damage that results in Chinese hamster ovary cells in vitro from imaging them with two-photon excited autofluorescence. The CPD levels are quantified by immunofluorescent staining. We further evaluate the extent of CPD damage with respect to varied wavelength, pulse width at focal plane, and pixel dwell time as compared with more pronounced damage from UV sources. While CPD damage has been expected to result from three-photon absorption, our results reveal that CPDs are induced by competing twoand three-photon absorption processes, where the former accesses UVA absorption band. This finding is independently confirmed by nonlinear dependencies of damage on laser power, wavelength, and pulse width. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE).},
note = {cited By (since 1996) 0},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Hafrén2012817,
title = {Optical properties of thermomechanical pulp (TMP) obtained from sulfite-pretreated Norway spruce with focus on two-photon spectral imaging (TPSI)},
author = {Jonas Hafrén and Erik Nelsson and Hans C. Gerritsen and Arjen N. Bader},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84869416158&partnerID=40&md5=788802190d7fc7d0b9af3dd9e425b8d3},
year  = {2012},
date = {2012-01-01},
journal = {Holzforschung},
volume = {66},
number = {7},
pages = {817-824},
abstract = {Chips of Norway spruce have been impregnated with Na2SO 3 and refined at two specific energy consumptions levels at full mill scale. The optical properties of thermomechanical pulps (TMPs) obtained were analyzed in terms of brightness, light scattering, opacity, and autofluorescence by spectral imaging. Even at low sulfite dosage (0.24% sulfite by dry weight) light absorption was reduced, and the brightness was elevated, and a clear dose-response effect was observed. Two-photon spectral imaging (TPSI) showed that sulfonation, impregnation, and refining affect the fluorescence properties differently. Compared to native wood, both processed wood chips and pulp fibers revealed blue-shifted fluorescence maxima, a characteristic of shortened conjugated systems. Two subpopulations of fibers with different optical properties were observed, and the fluorescence of one fiber population was red shifted. Copyright © by Walter de Gruyter.},
note = {cited By (since 1996) 0},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@conference{Antonello2012,
title = {Data driven identification and aberration correction for model based sensorless adaptive optics},
author = {Jacopo Antonello and Rufus Fraanje and Hong Song and Michel H.G. Verhaegen and Hans C. Gerritsen and Christoph U. Keller and Tim van Werkhoven},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84861929346&partnerID=40&md5=48c56c6ae5a0b37bfdaa2aa70fe8274c},
year  = {2012},
date = {2012-01-01},
journal = {Proceedings of SPIE - The International Society for Optical Engineering},
volume = {8436},
abstract = {Wavefront sensorless adaptive optics methodologies are considered in many applications where the deployment of a dedicated wavefront sensor is inconvenient, such as in fluorescence microscopy. In these methodologies, aberration correction is achieved by sequentially changing the settings of the adaptive optical element until a predetermined imaging quality metric is optimised. Reducing the time required for this optimisation is a challenge. In this paper, a two stage data driven optimisation procedure is presented and validated in a laboratory environment. In the first stage, known aberrations are introduced by a deformable mirror and the corresponding intensities are measured by a photodiode masked by a pinhole. A generic quadratic metric is fitted to this collection of aberrations and intensity measurements. In the second stage, this quadratic metric is used in order to estimate and correct for optical aberrations. A closed form expression for the optimisation of the quadratic metric is derived by solving a linear system of equations. This requires a minimum of N +1 pairs of deformable mirror settings and intensity measurements, where N is the number of modes of the aberrations. © 2012 SPIE.},
note = {cited By (since 1996) 1},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@article{Fereidouni201212729,
title = {Spectral phasor analysis allows rapid and reliable unmixing of fluorescence microscopy spectral images},
author = {Farzad Fereidouni and Arjen N. Bader and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84863773951&partnerID=40&md5=d006a9341028995b35df3c3e49d740eb},
year  = {2012},
date = {2012-01-01},
journal = {Optics Express},
volume = {20},
number = {12},
pages = {12729-12741},
abstract = {A new global analysis algorithm to analyse (hyper-) spectral images is presented. It is based on the phasor representation that has been demonstrated to be very powerful for the analysis of lifetime imaging data. In spectral phasor analysis the fluorescence spectrum of each pixel in the image is Fourier transformed. Next, the real and imaginary components of the first harmonic of the transform are employed as X and Y coordinates in a scatter (spectral phasor) plot. Importantly, the spectral phasor representation allows for rapid (real time) semi-blind spectral unmixing of up to three components in the image. This is demonstrated on slides with fixed cells containing three fluorescent labels. In addition the method is used to analyse autofluorescence of cells in a fresh grass blade. It is shown that the spectral phasor approach is compatible with spectral imaging data recorded with a low number of spectral channels. ©2012 Optical Society of America.},
note = {cited By (since 1996) 1},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@conference{VanWerkhoven2012,
title = {Coherence-gated wavefront sensing for microscopy using fringe analysis},
author = {Tim van Werkhoven and Hoa H. Truong and Jacopo Antonello and Rufus Fraanje and Hans C. Gerritsen and Michel H.G. Verhagen and Christoph U. Keller},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84859575448&partnerID=40&md5=e916490497126bed67217780e89f9f12},
year  = {2012},
date = {2012-01-01},
journal = {Proceedings of SPIE - The International Society for Optical Engineering},
volume = {8253},
abstract = {We have implemented a coherence-gated wavefront sensor on a two-photon excitation microscope. We used the backscattered near-infrared light from the sample to interfere with an optically flat reference beam. By applying a known wavefront tilt in the reference beam, a fringe pattern emerged on the camera. The deformation of the wavefront due to the turbid media under study warps the fringe pattern, similar to frequency modulation. Through Fourier transform analysis of the modulated fringe pattern we were able to determine the wavefront aberrations induced by synthetic and biological samples. By defocussing the microscope objective and measuring the wavefront deformation we established that the errors are reproducible to within λ/227 for the defocus mode. © 2012 SPIE.},
note = {cited By (since 1996) 0},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@article{Groeneveld2012749,
title = {Highly luminescent (Zn,Cd)Te/CdSe colloidal heteronanowires with tunable electron-hole overlap},
author = {Esther Groeneveld and Susanne van Berkum and Matti M. van Schooneveld and Alexandre Gloter and Johannes D. Meeldijk and Dave J. van den Heuvel and Hans C. Gerritsen and Celso de Mello-Donega},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84856966346&partnerID=40&md5=9e3e8969e44eb2805065f4733e934adf},
year  = {2012},
date = {2012-01-01},
journal = {Nano Letters},
volume = {12},
number = {2},
pages = {749-757},
abstract = {We report the synthesis of ultranarrow (Zn,Cd)Te/CdSe colloidal heteronanowires, using ZnTe magic size clusters as seeds. The wire formation starts with a partial Zn for Cd cation exchange, followed by self-organization into segmented heteronanowires. Further growth occurs by inclusion of CdSe. The heteronanowires emit in the 530 to 760 nm range with high quantum yields. The electron-hole overlap decreases with increasing CdSe volume fraction, allowing the optical properties to be controlled by adjusting the heteronanowire composition. © 2012 American Chemical Society.},
note = {cited By (since 1996) 6},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Karreman20121428,
title = {Integrated laser and electron microscopy correlates structure of fluid catalytic cracking particles to Brønsted acidity},
author = {Matthia A. Karreman and Inge L.C. Buurmans and John W. Geus and Alexandra V. Agronskaia and Javier Ruiz-Martínez and Hans C. Gerritsen and Bert M. Weckhuysen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84856448244&partnerID=40&md5=48a205b66e1adb856ca1c10359c379ce},
year  = {2012},
date = {2012-01-01},
journal = {Angewandte Chemie - International Edition},
volume = {51},
number = {6},
pages = {1428-1431},
abstract = {Cracking the crackers: Integrated laser and electron microscopy was applied to study individual fluid catalytic cracking catalyst particles (see picture) deactivated according to an industrially relevant protocol. New insights have been obtained by correlating Brønsted acidity changes, visualized using fluorescence microscopy, with structural transformations in the zeolite and matrix components, as observed with electron microscopy. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.},
note = {cited By (since 1996) 5},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Kovacic2012,
title = {Design and construction of a one-dimensional DNA track for an artificial molecular motor},
author = {Suzana Kovacic and Laleh Samii and Dek N. Woolfson and Paul M.G. Curmi and Heiner Linke and Nancy R. Forde and Gerhard A. Blab},
url = {http://www.hindawi.com/journals/jnm/2012/109238/},
doi = {10.1155/2012/109238},
issn = {16874110},
year  = {2012},
date = {2012-01-01},
journal = {Journal of Nanomaterials},
volume = {2012},
abstract = {DNA is a versatile heteropolymer that shows great potential as a building block for a diverse array of nanostructures. We present here a solution to the problem of designing and synthesizing a DNA-based nanostructure that will serve as the track along which an artificial molecular motor processes. This one-dimensional DNA track exhibits periodically repeating elements that provide specific binding sites for the molecular motor. Besides these binding elements, additional sequences are necessary to label specific regions within the DNA track and to facilitate track construction. Designing an ideal DNA track sequence presents a particular challenge because of the many variable elements that greatly expand the number of potential sequences from which the ideal sequence must be chosen. In order to find a suitable DNA sequence, we have adapted a genetic algorithm which is well suited for a large but sparse search space. This algorithm readily identifies long DNA sequences that include all the necessary elements to both facilitate DNA track construction and to present appropriate binding sites for the molecular motor. We have successfully experimentally incorporated the sequence identified by the algorithm into a long DNA track meeting the criteria for observation of the molecular motor's activity. © 2012 Suzana Kovacic et al.},
keywords = {Algorithms; DNA; Linear motors; Nanostructures, Binding elements; Building blockes; Design and construction; DNA-based nanostructures; Molecular motors; Search spaces; Specific binding; Track construction, DNA sequences},
pubstate = {published},
tppubtype = {article}
}
@article{Fereidouni2011248,
title = {A modified phasor approach for analyzing time-gated fluorescence lifetime images},
author = {Farzad Fereidouni and Alessandro Esposito and Gerhard A. Blab and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-81255168136&partnerID=40&md5=8c5891d4a795370fea469dc374564281},
year  = {2011},
date = {2011-01-01},
journal = {Journal of Microscopy},
volume = {244},
number = {3},
pages = {248-258},
abstract = {Fluorescence lifetime imaging is a versatile tool that permits mapping the biochemical environment in the cell. Among various fluorescence lifetime imaging techniques, time-correlated single photon counting and time-gating methods have been demonstrated to be very efficient and robust for the imaging of biological specimens. Recently, the phasor representation of lifetime images became popular because it provides an intuitive graphical view of the fluorescence lifetime content of the images and, when used for global analysis, significantly improves the overall S/N of lifetime analysis. Compared to time-correlated single photon counting, time gating methods can provide higher count rates (∼10 MHz) but at the cost of truncating and under sampling the decay curve due to the limited number of gates commonly used. These limitations also complicate the implementation of the phasor analysis for time-gated data. In this work, we propose and validate a theoretical framework that overcomes these problems. This modified approach is tested on both simulated lifetime images and on cells. We demonstrate that this method is able to retrieve two lifetimes from time gating data that cannot be resolved using standard (non-global) fitting techniques. The new approach increases the information that can be obtained from typical measurements and simplifies the analysis of fluorescence lifetime imaging data. © 2011 Utrecht University Journal of Microscopy © 2011 Royal Microscopical Society.},
note = {cited By (since 1996) 4},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Hafrén2011372,
title = {Two-photon autofluorescence spectral imaging applied to probe process-effects in thermomechanical pulp refining},
author = {Jonas Hafrén and Dino Muhić and Hans C. Gerritsen and Arjen N. Bader},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84855522085&partnerID=40&md5=36170ed2f702bc3a5d28fb0ce8eed179},
year  = {2011},
date = {2011-01-01},
journal = {Nordic Pulp and Paper Research Journal},
volume = {26},
number = {4},
pages = {372-379},
abstract = {Norway spruce wood pulps were produced in full industrial scale trials at different thermomechanical pulp refining conditions, such as plate gap, housing pressures and energy consumption levels. To investigate the effects of these refining conditions on the lingocellulosic matrix in fines and fibers, we applied high-resolution spectral imaging in a two-photon fluorescence microscope and compared with conventional pulp and paper analyses (strength, freeness etc.). The fluorescence spectra of lignin in native wood and fibersand fines from pulps showed that spatial- and spectral heterogeneities can be observed using two-photon autofluorescence spectral imaging, and successfully probed on a microscopic level. Moreover, it was shown that wood autofluorescence depends on fiber morphology and becomes red-shifted by increased temperature, but the fluorescence spectrum of TMP long fiber fraction shifted towards blue by increased refining pressure.},
note = {cited By (since 1996) 2},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{vanderPoel20111634,
title = {Hyperacidification of trans-golgi network and endo/lysosomes in melanocytes by glucosylceramide-dependent V-ATPase activity},
author = {Seléne van der Poel and Jasja Wolthoorn and Dave J. van den Heuvel and Maarten R. Egmond and Sophie Groux-Degroote and Sylvia Neumann and Hans C. Gerritsen and Gerrit van Meer and Hein Sprong},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-80053594845&partnerID=40&md5=15d915d33f87d797725c167358e89204},
year  = {2011},
date = {2011-01-01},
journal = {Traffic},
volume = {12},
number = {11},
pages = {1634-1647},
abstract = {Sphingolipids are considered to play a key role in protein sorting and membrane trafficking. In melanocytic cells, sorting of lysosomal and melanosomal proteins requires the sphingolipid glucosylceramide (GlcCer). This sorting information is located in the lumenal domain of melanosomal proteins. We found that two processes dependent on lumenal pH, protein sialylation and lysosomal acid lipase (LAL) activity were aberrant in GM95 melanocyte cells, which do not produce glycosphingolipids. Using fluorescence lifetime imaging microscopy (FLIM), we found that the lumenal pH in the trans-Golgi network and lysosomes of wild-type melanocyte MEB4 cells are >1 pH unit lower than GM95 cells and fibroblasts. In addition to the lower pH found in vivo, the in vitro activity of the proton pump, the vacuolar-type H +-translocating ATPase (V-ATPase), was twofold higher in MEB4 compared to GM95 cells. The apparent K i for inhibition of the V-ATPase by concanamycin A and archazolid A, which share a common binding site on the c-ring, was lower in glycosphingolipid-deficient GM95 cells. No difference between the MEB4 and GM95 cells was found for the V-ATPase inhibitors apicularen A and salicylihalimide. We conclude that hyperacidification in MEB4 cells requires glycosphingolipids and propose that low pH is necessary for protein sorting and melanosome biogenesis. Furthermore, we suggest that glycosphingolipids are indirectly involved in protein sorting and melanosome biogenesis by stimulating the proton pump, possibly through binding of GlcCer. These experiments establish, for the first time, a link between pH, glycosphingolipids and melanosome biogenesis in melanocytic MEB4 cells, to suggest a role for glycosphingolipids in hyperacidification in melanocytes. © 2011 John Wiley & Sons A/S.},
note = {cited By (since 1996) 3},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Elstak20111570,
title = {The munc13-4-rab27 complex is specifically required for tethering secretory lysosomes at the plasma membrane},
author = {Edo D. Elstak and Maaike Neeft and Nadine T. Nehme and Jarno Voortman and Marc Cheung and Monireh Goodarzifard and Hans C. Gerritsen and Paul M.P. van Bergen en Henegouwen and Isabelle Callebaut and Geneviève de Saint Basile and Peter D. van der Sluijs},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-80051639052&partnerID=40&md5=4369791a6d23655b138e96021245dbfc},
year  = {2011},
date = {2011-01-01},
journal = {Blood},
volume = {118},
number = {6},
pages = {1570-1578},
abstract = {Cytotoxic T lymphocytes (CTLs) kill target cells through the polarized release of lytic molecules from secretory lysosomes. Loss of munc13-4 function inhibits this process and causes familial hemophagocytic lymphohistiocytosis type 3 (FHL3). munc13-4 binds rab27a, but the necessity of the complex remains enigmatic, because studies in knockout models suggest separate functions. In the present study, we describe a noncanonical rab27abinding motif in the N-terminus of munc13-4. Point mutants in this sequence have severely impaired rab27a binding, allowing dissection of rab27a requirements in munc13-4 function. The munc13- 4 - rab27a complex is not needed for secretory lysosome maturation, as shown by complementation in CTLs from FHL3 patients and in a mast cell line silenced for munc13-4. In contrast, fusion of secretory lysosomes with, and content release at the plasma membrane during degranulation, strictly required the munc13-4 - rab27a complex. Total internal reflection fluorescence microscopy imaging revealed that the complex corrals motile secretory lysosomes beneath the plasma membrane during degranulation and controls their docking. The propensity to stall motility of secretory lysosomes is lost in cells expressing munc13-4 point mutants that do not bind rab27. In summary, these results uncovered a mechanism for tethering secretory lysosomes to the plasma membrane that is essential for degranulation in immune cells. © 2011 by The American Society of Hematology.},
note = {cited By (since 1996) 12},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Karreman2011806,
title = {VIS2FIX: A high-speed fixation method for immuno-electron microscopy},
author = {Matthia A. Karreman and Elly G. van Donselaar and Hans C. Gerritsen and Cornelis T. Verrips and Ariel J. Verkleij},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-79958767353&partnerID=40&md5=22d586033fa1a33efc511a091f5bbb9e},
year  = {2011},
date = {2011-01-01},
journal = {Traffic},
volume = {12},
number = {7},
pages = {806-814},
abstract = {Immuno-transmission electron microscopy (TEM) is the technique of choice for high-resolution localization of proteins in fixed specimen. Here we introduce 2 novel methods for the fixation of sections from cryo-immobilized samples that result in excellent ultrastructural preservation. These high-speed fixation techniques, both called VIS2FIX, allow for a reduction in sample preparation time from at least 1 week to only 8 h. The methods were validated in immuno-TEM experiments on THP-1 monocytes, human umbilical vein endothelial cells (HUVECs) and Madin-Darby canine kidney (MDCK-II) cells. The fixation and retention of neutral lipids is demonstrated, offering unique prospects for the application of immuno-TEM in the lipidomics field. Furthermore, the VIS2FIX methods were successfully employed in correlative fluorescence and electron microscopy. © 2011 John Wiley & Sons A/S.},
note = {cited By (since 1996) 3},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Palero20111030,
title = {In vivo monitoring of protein-bound and free NADH during ischemia by nonlinear spectral imaging microscopy},
author = {Jonathan A. Palero and Arjen N. Bader and Henriëtte S. de Bruijn and Angélique van der Ploeg - van den Heuvel and Henricus J.C.M. Sterenborg and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84863428199&partnerID=40&md5=7cbb65a0c3fbae0aa0311fb8c8effdb2},
year  = {2011},
date = {2011-01-01},
journal = {Biomedical Optics Express},
volume = {2},
number = {5},
pages = {1030-1039},
abstract = {Nonlinear spectral imaging microscopy (NSIM) allows simultaneous morphological and spectroscopic investigation of intercellular events within living animals. In this study we used NSIM for in vivo timelapse in-depth spectral imaging and monitoring of protein-bound and free reduced nicotinamide adenine dinucleotide (NADH) in mouse keratinocytes following total acute ischemia for 3.3 h at ~3 min time intervals. The high spectral resolution of NSIM images allows discrimination between the twophoton excited fluorescence emission of protein-bound and free NAD(P)H by applying linear spectral unmixing to the spectral image data. Results reveal the difference in the dynamic response between protein-bound and free NAD(P)H to ischemia-induced hypoxia/anoxia. Our results demonstrate the capability of nonlinear spectral imaging microscopy in unraveling dynamic cellular metabolic events within living animals for long periods of time. © 2011 Optical Society of America.},
note = {cited By (since 1996) 5},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Bader2011475,
title = {Homo-FRET imaging as a tool to quantify protein and lipid clustering},
author = {Arjen N. Bader and Sandra Hoetzl and Erik G. Hofman and Jarno Voortman and Paul M.P. van Bergen en Henegouwen and Gerrit van Meer and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-79951971437&partnerID=40&md5=305c3c3d739b45ae88a7b9a79b445fdd},
year  = {2011},
date = {2011-01-01},
journal = {ChemPhysChem},
volume = {12},
number = {3},
pages = {475-483},
abstract = {Homo-FRET, Förster resonance energy transfer between identical fluorophores, can be conveniently measured by observing its effect on the fluorescence anisotropy. This review aims to summarize the possibilities of fluorescence anisotropy imaging techniques to investigate clustering of identical proteins and lipids. Homo-FRET imaging has the ability to determine distances between fluorophores. In addition it can be employed to quantify cluster sizes as well as cluster size distributions. The interpretation of homo-FRET signals is complicated by the fact that both the mutual orientations of the fluorophores and the number of fluorophores per cluster affect the fluorescence anisotropy in a similar way. The properties of the fluorescence probes are very important. Taking these properties into account is critical for the correct interpretation of homo-FRET signals in protein-and lipid-clustering studies. This is be exemplified by studies on the clustering of the lipid raft markers GPI and K-ras, as well as for EGF receptor clustering in the plasma membrane. © 2011 Wiley-VCH Verlag GmbH & Co. KGaA.},
note = {cited By (since 1996) 12},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Bader2011365,
title = {Fast nonlinear spectral microscopy of in vivo human skin},
author = {Arjen N. Bader and Ana Maria Pena and Johan van Voskuilen and Jonathan A. Palero and Frédéric Leroy and Anna Colonna and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-79961133626&partnerID=40&md5=31a005b0be9706e4719b42383c6ccf10},
year  = {2011},
date = {2011-01-01},
journal = {Biomedical Optics Express},
volume = {2},
number = {2},
pages = {365-373},
abstract = {An optimized system for fast, high-resolution spectral imaging of in vivo human skin is developed and evaluated. The spectrograph is composed of a dispersive prism in combination with an electron multiplying CCD camera. Spectra of autofluorescence and second harmonic generation (SHG) are acquired at a rate of 8 kHz and spectral images within seconds. Image quality is significantly enhanced by the simultaneous recording of background spectra. In vivo spectral images of 224 × 224 pixels were acquired, background corrected and previewed in real RGB color in 6.5 seconds. A clear increase in melanin content in deeper epidermal layers in in vivo human skin was observed. © 2011 Optical Society of America.},
note = {cited By (since 1996) 9},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Esposito20112546,
title = {Design and application of a confocal microscope for spectrally resolved anisotropy imaging},
author = {Alessandro Esposito and Arjen N. Bader and Simon C. Schlachter and Dave J. van den Heuvel and Gabriele S. Kaminski Schierle and Ashok R. Venkitaraman and Clemens F. Kaminski and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-79851473652&partnerID=40&md5=4fc53d3dd4f226d0b892b83c25124520},
year  = {2011},
date = {2011-01-01},
journal = {Optics Express},
volume = {19},
number = {3},
pages = {2546-2555},
abstract = {Biophysical imaging tools exploit several properties of fluorescence to map cellular biochemistry. However, the engineering of a cost-effective and user-friendly detection system for sensing the diverse properties of fluorescence is a difficult challenge. Here, we present a novel architecture for a spectrograph that permits integrated characterization of excitation, emission and fluorescence anisotropy spectra in a quantitative and efficient manner. This sensing platform achieves excellent versatility of use at comparatively low costs. We demonstrate the novel optical design with example images of plant cells and of mammalian cells expressing fluorescent proteins undergoing energy transfer. © 2011 Optical Society of America.},
note = {cited By (since 1996) 3},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Farré201121370,
title = {Positional stability of holographic optical traps},
author = {Arnau Farré and Marjan Shayegan and Carol López-Quesada and Gerhard A. Blab and Mario Montes-Usategui and Nancy R. Forde and Estela Martín-Badosa},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-80054936600&partnerID=40&md5=ee19273928a3c3caa6cbf489d1cac16f},
doi = {10.1364/OE.19.021370},
year  = {2011},
date = {2011-01-01},
journal = {Optics Express},
volume = {19},
number = {22},
pages = {21370-21384},
note = {cited By 6},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Samii2011,
title = {Time-dependent motor properties of multipedal molecular spiders},
author = {Laleh Samii and Gerhard A. Blab and Elizabeth H.C. Bromley and Heiner Linke and Paul M.G. Curmi and Martin J. Zuckermann and Nancy R. Forde},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-80053028643&partnerID=40&md5=4cd91381870565242d9375cb20679ce3},
doi = {10.1103/PhysRevE.84.031111},
year  = {2011},
date = {2011-01-01},
journal = {Physical Review E - Statistical, Nonlinear, and Soft Matter Physics},
volume = {84},
number = {3},
note = {cited By 9},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Hofman201039481,
title = {Ligand-induced EGF receptor oligomerization is kinase-dependent and enhances internalization},
author = {Erik G. Hofman and Arjen N. Bader and Jarno Voortman and Dave J. van den Heuvel and Sara Sigismund and Ariel J. Verkleij and Hans C. Gerritsen and Paul M.P. van Bergen en Henegouwen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-78649814933&partnerID=40&md5=b8f61b2fff2cbe95a6b8853a63f3bcbf},
year  = {2010},
date = {2010-01-01},
journal = {Journal of Biological Chemistry},
volume = {285},
number = {50},
pages = {39481-39489},
abstract = {The current activation model of the EGF receptor (EGFR) predicts that binding of EGF results in dimerization and oligomerization of the EGFR, leading to the allosteric activation of the intracellular tyrosine kinase. Little is known about the regulatory mechanism of receptor oligomerization. In this study, we have employed FRET between identical fluorophores (homo-FRET) to monitor the dimerization and oligomerization state of the EGFR before and after receptor activation. Our data show that, in the absence of ligand, ∼40% of the EGFR molecules were present as inactive dimers or predimers. The monomer/predimer ratio was not affected by deletion of the intracellular domain. Ligand binding induced the formation of receptor oligomers, which were found in both the plasma membrane and intracellular structures. Ligand-induced oligomerization required tyrosine kinase activity and nine different tyrosine kinase substrate residues. This indicates that the binding of signaling molecules to activated EGFRs results in EGFR oligomerization. Induction of EGFR predimers or preoligomers using the EGFR fused to the FK506-binding protein did not affect signaling but was found to enhance EGF-induced receptor internalization. Our data show that EGFR oligomerization is the result of EGFR signaling and enhances EGFR internalization. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc.},
note = {cited By (since 1996) 11},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Skajaa20105131,
title = {Quantum dot and Cy5.5 labeled nanoparticles to investigate lipoprotein biointeractions via Förster resonance energy transfer},
author = {Torjus Skajaa and Yiming Zhao and Dave J. van den Heuvel and Hans C. Gerritsen and David P. Cormode and Rolf Koole and Matti M. van Schooneveld and Jan Andries Post and Edward A. Fisher and Zahi Adel Fayad and Celso de Mello-Donega and Andries Meijerink and Willem J.M. Mulder},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-78650123329&partnerID=40&md5=3498284304110eb62a626e7163339a69},
year  = {2010},
date = {2010-01-01},
journal = {Nano Letters},
volume = {10},
number = {12},
pages = {5131-5138},
abstract = {The study of lipoproteins, natural nanoparticles comprised of lipids and apolipoproteins that transport fats throughout the body, is of key importance to better understand, treat, and prevent cardiovascular disease. In the current study, we have developed a lipoprotein-based nanoparticle that consists of a quantum dot (QD) core and Cy5.5 labeled lipidic coating. The methodology allows judicious tuning of the QD/Cy5.5 ratio, which enabled us to optimize Förster resonance energy transfer (FRET) between the QD core and the Cy5.5-labeled coating. This phenomenon allowed us to study lipoprotein- lipoprotein interactions, lipid exchange dynamics, and the influence of apolipoproteins on these processes. Moreover, we were able to study HDL-cell interactions and exploit FRET to visualize HDL association with live macrophage cells. © 2010 American Chemical Society.},
note = {cited By (since 1996) 14},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Kuwada2010479,
title = {A classical Master equation approach to modeling an artificial protein motor},
author = {Nathan J. Kuwada and Gerhard A. Blab and Heiner Linke},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-77957750193&partnerID=40&md5=eb39d2cf0cdf264aa9c807cc40f7d15e},
doi = {10.1016/j.chemphys.2010.05.009},
year  = {2010},
date = {2010-01-01},
journal = {Chemical Physics},
volume = {375},
number = {2-3},
pages = {479-485},
note = {cited By 9},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Farré2010224,
title = {Stretching single DNA molecules to demonstrate high-force capabilities of holographic optical tweezers},
author = {Arnau Farré and Astrid van der Horst and Gerhard A. Blab and Benjamin P.B. Downing and Nancy R. Forde},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-77950880891&partnerID=40&md5=de8070d902b91ff9d044ed2d8a48ac6e},
doi = {10.1002/jbio.200900107},
year  = {2010},
date = {2010-01-01},
journal = {Journal of Biophotonics},
volume = {3},
number = {4},
pages = {224-233},
note = {cited By 18},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Bader20092613,
title = {Homo-FRET imaging enables quantification of protein cluster sizes with subcellular resolution},
author = {Arjen N. Bader and Erik G. Hofman and Jarno Voortman and Paul M.P. van Bergen en Henegouwen and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-72249114997&partnerID=40&md5=394837b415f9eb9de33ab9febe9def2f},
year  = {2009},
date = {2009-01-01},
journal = {Biophysical Journal},
volume = {97},
number = {9},
pages = {2613-2622},
abstract = {Fluorescence-anisotropy-based homo-FRET detection methods can be employed to study clustering of identical proteins in cells. Here, the potential of fluorescence anisotropy microscopy for the quantitative imaging of protein clusters with subcellular resolution is investigated. Steady-state and time-resolved anisotropy detection and both one- and two-photon excitation methods are compared. The methods are evaluated on cells expressing green fluorescent protein (GFP) constructs that contain one or two FK506-binding proteins. This makes it possible to control dimerization and oligomerization of the constructs and yields the experimental relation between anisotropy and cluster size. The results show that, independent of the experimental method, the commonly made assumption of complete depolarization after a single energy transfer step is not valid here. This is due to a nonrandom relative orientation of the fluorescent proteins. Our experiments show that this relative orientation is restricted by interactions between the GFP barrels. We describe how the experimental relation between anisotropy and cluster size can be employed in quantitative cluster size imaging experiments of other GFP fusions. Experiments on glycosylphosphatidylinisotol (GPI)-anchored proteins reveal that GPI forms clusters with an average size of more than two subunits. For epidermal growth factor receptor (EGFR), we observe that ∼40% of the unstimulated receptors are present in the plasma membrane as preexisting dimers. Both examples reveal subcellular heterogeneities in cluster size and distribution. © 2009 by the Biophysical Society.},
note = {cited By (since 1996) 32},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Regan-Klapisz20094225,
title = {Golgi-associated cPLA2α regulates endothelial cell-cell junction integrity by controlling the trafficking of transmembrane junction proteins},
author = {Elsa Regan-Klapisz and Vincent J.D. Krouwer and Miriam Langelaar-Makkinje and Laxman Nallan and Michael H. Gelb and Hans C. Gerritsen and Ariel J. Verkleij and Jan Andries Post},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-70350214396&partnerID=40&md5=8acfddd198ad19a78a872a5df5826771},
year  = {2009},
date = {2009-01-01},
journal = {Molecular Biology of the Cell},
volume = {20},
number = {19},
pages = {4225-4234},
abstract = {In endothelial cells specifically, cPLA2α translocates from the cytoplasm to the Golgi complex in response to cell confluence. Considering the link between confluence and cell-cell junction formation, and the emerging role of cPLA2α in intracellular trafficking, we tested whether Golgi-associated cPLA2α is involved in the trafficking of junction proteins. Here, we show that the redistribution of cPLA2α from the cytoplasm to the Golgi correlates with adherens junction maturation and occurs before tight junction formation. Disruption of adherens junctions using a blocking anti-VE-cadherin antibody reverses the association of cPLA2α with the Golgi. Silencing of cPLA2α and inhibition of cPLA2α enzymatic activity using various inhibitors result in the diminished presence of the transmembrane junction proteins VE-cadherin, occludin, and claudin-5 at cell-cell contacts, and in their accumulation at the Golgi. Altogether, our data support the idea that VE-cadherin triggers the relocation of cPLA2α to the Golgi and that in turn, Golgi-associated cPLA2α regulates the transport of transmembrane junction proteins through or from the Golgi, thereby controlling the integrity of endothelial cell-cell junctions. © 2009 by The American Society for Cell Biology.},
note = {cited By (since 1996) 14},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Karreman2009287,
title = {Discovery of a new RNA-containing nuclear structure in UVC-induced apoptotic cells by integrated laser electron microscopy},
author = {Matthia A. Karreman and Alexandra V. Agronskaia and Ariel J. Verkleij and Fons F.M. Cremers and Hans C. Gerritsen and Bruno M. Humbel},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-64749101189&partnerID=40&md5=496784ab637e36f3e134ef30494cb213},
year  = {2009},
date = {2009-01-01},
journal = {Biology of the Cell},
volume = {101},
number = {5},
pages = {287-299},
abstract = {Background information. Treatment of cells with UVC radiation leads to the formation of DNA cross-links which, if not repaired, can lead to apoptosis. γ-H2AX and cleaved caspase 3 are proteins formed during UVC-induced DNA damage and apoptosis respectively. The present study sets out to identify early morphological markers of apoptosis using a new method of correlative microscopy, ILEM (integrated laser electron microscopy). Cleaved caspase 3 and γ-H2AX were immunofluorescently labelled to mark the cells of interest. These cells were subsequently searched in the fluorescence mode of the ILEM and further analysed at high resolution with TEM (transmission electron microscopy). Results. Following the treatment of HUVECs (human umbilical vein endothelial cells) with UVC radiation, in the majority of the cells γ-H2AX was formed, whereas only in a subset of cells caspase 3 was activated. In severely damaged cells with high levels of γ-H2AX a round, electron-dense nuclear structure was found, which was hitherto not identified in UV-stressed cells. This structure exists only in nuclei of cells containing cleaved caspase 3 and is present during all stages of the apoptotic process. Energy-loss imaging showed that the nuclear structure accumulates phosphorus, indicating that it is rich in nucleic acids. Because the nuclear structure did not label for DNA and was not affected by regressive EDTA treatment, it is suggested that the UV-induced nuclear structure contains a high amount of RNA. Conclusions. Because the UV-induced nuclear structure was only found in cells labelled for cleaved caspase 3 it is proposed as an electron microscopic marker for all stages of apoptosis. Such a marker will especially facilitate the screening for early apoptotic cells, which lack the well-known hallmarks of apoptosis within a cell population. It also raises new questions on the mechanisms involved in the UV-induced apoptotic pathway.},
note = {cited By (since 1996) 13},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Hofman2009213,
title = {EGF induces rapid reorganization of plasma membrane microdomains},
author = {Erik G. Hofman and Arjen N. Bader and Hans C. Gerritsen and Paul M.P. van Bergen en Henegouwen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-76549095872&partnerID=40&md5=4a19464f658b42a15625ae2d8122019b},
year  = {2009},
date = {2009-01-01},
journal = {Communicative and Integrative Biology},
volume = {2},
number = {3},
pages = {213-214},
abstract = {The plasma membrane of mammalian cells is composed of a great variety of different lipids which are laterally organized into lipid domains. The segregation of lipids into domains has been studied in great detail in vesicles but domain formation of lipids in the plasma membrane of live cells is still unclear. We have previously used fluorescence lifetime imaging microscopy to study the colocalization of the receptor for EGF with the ganglioside GM1 and the GPI-anchored green fluorescent protein. Here we have used this technology to study the effect of EGF on the organization of GM1 in the plasma membrane. Our data show that stimulation of the cell with EGF induces rapidly a strong increase in colocalization of GM1 molecules, suggesting the formation of large lipid domains. These results support the notion that activation of EGFR signaling may result in the formation of signaling platforms.},
note = {cited By (since 1996) 1},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Gerritsen200995,
title = {Chapter 3 Time domain FLIM: Theory, instrumentation, and data analysis},
author = {Hans C. Gerritsen and Alexandra V. Agronskaia and Arjen N. Bader and Alessandro Esposito},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-59249096905&partnerID=40&md5=533900d71995ce08bef17c58aa66593b},
year  = {2009},
date = {2009-01-01},
journal = {Laboratory Techniques in Biochemistry and Molecular Biology},
volume = {33},
number = {C},
pages = {95-132},
note = {cited By (since 1996) 2},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Chen20094701,
title = {Stretching submicron biomolecules with constant-force axial optical tweezers},
author = {Yi Fan Chen and Gerhard A. Blab and Jens Christian Meiners},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-68949114442&partnerID=40&md5=21b94c0763c8390f73ea62f7cdfcbcf7},
doi = {10.1016/j.bpj.2009.03.009},
year  = {2009},
date = {2009-01-01},
journal = {Biophysical Journal},
volume = {96},
number = {11},
pages = {4701-4708},
note = {cited By 39},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Bromley2009204,
title = {The tumbleweed: Towards a synthetic protein motor},
author = {Elizabeth H.C. Bromley and Nathan J. Kuwada and Martin J. Zuckermann and Roberta Donadini and Laleh Samii and Gerhard A. Blab and Greg J. Gemmen and Benjamin J. Lopez and Paul M.G. Curmi and Nancy R. Forde and Dek N. Woolfson and Heiner Linke},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-70350665969&partnerID=40&md5=8d9fbb9cf82eeef7e51b07fbbc509cf8},
doi = {10.2976/1.3111282},
year  = {2009},
date = {2009-01-01},
journal = {HFSP Journal},
volume = {3},
number = {3},
pages = {204-212},
note = {cited By 22},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Palero2008,
title = {Design and implementation of a sensitive high-resolution nonlinear spectral imaging microscope},
author = {Jonathan A. Palero and Gwendal Latouche and Henriëtte S. de Bruijn and Angélique van der Ploeg - van den Heuvel and Henricus J.C.M. Sterenborg and Hans C. Gerritsen },
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-55149097757&partnerID=40&md5=68cb3f124f6885e89034c49e00093dcc},
year  = {2008},
date = {2008-01-01},
journal = {Journal of Biomedical Optics},
volume = {13},
number = {4},
abstract = {Live tissue nonlinear microscopy based on multiphoton autofluorescence and second harmonic emission originating from endogenous fluorophores and noncentrosymmetric-structured proteins is rapidly gaining interest in biomedical applications. The advantage of this technique includes high imaging penetration depth and minimal phototoxic effects on tissues. Because fluorescent dyes are not used, discrimination between different components within the tissue is challenging. We have developed a nonlinear spectral imaging microscope based on a home-built multiphoton microscope, a prism spectrograph, and a high-sensitivity CCD camera for detection. The sensitivity of the microscope was optimized for autofluorescence and second harmonic imaging over a broad wavelength range. Importantly, the spectrograph lacks an entrance aperture; this improves the detection efficiency at deeper lying layers in the specimen. Application to the imaging of ex vivo and in vivo mouse skin tissues showed clear differences in spectral emission between skin tissue layers as well as biochemically different tissue components. Acceptable spectral images could be recorded up to an imaging depth of ∼100μm. © 2008 Society of Photo-Optical Instrumentation Engineers.},
note = {cited By (since 1996) 8},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Palero20081422,
title = {In vivo nonlinear spectral imaging microscopy of visible and ultraviolet irradiated hairless mouse skin tissues},
author = {Jonathan A. Palero and Henriëtte S. de Bruijn and Angélique van der Ploeg - van den Heuvel and Henricus J.C.M. Sterenborg and Huib van Weelden and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-55149113465&partnerID=40&md5=46669922345fd57800b83a4ee15ea8cd},
year  = {2008},
date = {2008-01-01},
journal = {Photochemical and Photobiological Sciences},
volume = {7},
number = {11},
pages = {1422-1425},
abstract = {We demonstrate the capability of nonlinear spectral imaging microscopy (NSIM) in investigating ultraviolet and visible light induced effects on albino Skh:HR-1 hairless mouse skin non-invasively. © The Royal Society of Chemistry and Owner Societies.},
note = {cited By (since 1996) 13},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Agronskaia2008183,
title = {Integrated fluorescence and transmission electron microscopy},
author = {Alexandra V. Agronskaia and Jack A. Valentijn and Linda F. van Driel and Chris T.W.M. Schneijdenberg and Bruno M. Humbel and Paul M.P. van Bergen en Henegouwen and Ariel J. Verkleij and Abraham J. Koster and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-53949103753&partnerID=40&md5=08ec710890f0fa5af1f95a78e660352c},
year  = {2008},
date = {2008-01-01},
journal = {Journal of Structural Biology},
volume = {164},
number = {2},
pages = {183-189},
abstract = {Correlative microscopy is a powerful technique that combines the strengths of fluorescence microscopy and electron microscopy. The first enables rapid searching for regions of interest in large fields of view while the latter exhibits superior resolution over a narrow field of view. Routine use of correlative microscopy is seriously hampered by the cumbersome and elaborate experimental procedures. This is partly due to the use of two separate microscopes for fluorescence and electron microscopy. Here, an integrated approach to correlative microscopy is presented based on a laser scanning fluorescence microscope integrated in a transmission electron microscope. Using this approach the search for features in the specimen is greatly simplified and the time to carry out the experiment is strongly reduced. The potential of the integrated approach is demonstrated at room temperature on specimens of rat intestine cells labeled with AlexaFluor488 conjugated to wheat germ agglutinin and on rat liver peroxisomes immunolabeled with anti-catalase antibodies and secondary AlexaFluor488 antibodies and 10 nm protein A-gold. © 2008 Elsevier Inc. All rights reserved.},
note = {cited By (since 1996) 38},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Valentijn20081314,
title = {Novel methods for cryo-fluorescence microscopy permitting correlative cryo-electron microscopy},
author = {Jack A. Valentijn and Linda F. van Driel and Alexandra V. Agronskaia and Kevin Knoops and Roman I. Koning and Montserrat Barcena and Hans C. Gerritsen and Abraham J. Koster
},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-49549111578&partnerID=40&md5=fec1e22ceb2c51935d5922ea456c416e},
year  = {2008},
date = {2008-01-01},
journal = {Microscopy and Microanalysis},
volume = {14},
number = {SUPPL. 2},
pages = {1314-1315},
note = {cited By (since 1996) 2},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Hofman20082519,
title = {EGF induces coalescence of different lipid rafts},
author = {Erik G. Hofman and Mika O. Ruonala and Arjen N. Bader and Dave J. van den Heuvel and Jarno Voortman and Rob C. Roovers and Ariel J. Verkleij and Hans C. Gerritsen and Paul M.P. van Bergen en Henegouwen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-50249102207&partnerID=40&md5=8deb3bd4d65281456fbbf0a8fb7f61f1},
year  = {2008},
date = {2008-01-01},
journal = {Journal of Cell Science},
volume = {121},
number = {15},
pages = {2519-2528},
abstract = {The suggestion that microdomains may function as signaling platforms arose from the presence of growth factor receptors, such as the EGFR, in biochemically isolated lipid raft fractions. To investigate the role of EGFR activation in the organization of lipid rafts we have performed FLIM analyses using putative lipid raft markers such as ganglioside GM1 and glycosylphosphatidylinositol (GPI)-anchored GFP (GPI-GFP). The EGFR was labeled using single domain antibodies from Llama glama that specifically bind the EGFR without stimulating its kinase activity. Our FLIM analyses demonstrate a cholesterol-independent colocalization of GM1 with EGFR, which was not observed for the transferrin receptor. By contrast, a cholesterol-dependent colocalization was observed for GM1 with GPI-GFP. In the resting state no colocalization was observed between EGFR and GPI-GFP, but stimulation of the cell with EGF resulted in the colocalization at the nanoscale level of EGFR and GPI-GFP. Moreover, EGF induced the enrichment of GPI-GFP in a detergent-free lipid raft fraction. Our results suggest that EGF induces the coalescence of the two types of GM1-containing microdomains that might lead to the formation of signaling platforms.},
note = {cited By (since 1996) 46},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Esposito20073261,
title = {Optimizing frequency-domain fluorescence lifetime sensing for high-throughput applications: Photon economy and acquisition speed},
author = {Alessandro Esposito and Hans C. Gerritsen and Fred S. Wouters},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-36949023532&partnerID=40&md5=3c9b10ebd315a704a14fb7c435133825},
year  = {2007},
date = {2007-01-01},
journal = {Journal of the Optical Society of America A: Optics and Image Science, and Vision},
volume = {24},
number = {10},
pages = {3261-3273},
abstract = {The signal-to-noise ratio of a measurement is determined by the photon economy of the detection technique and the available photons that are emitted by the sample. We investigate the efficiency of various frequency-domain lifetime detection techniques also in relation to time-domain detection. Nonlinear effects are discussed that are introduced by the use of image intensifiers and by fluorophore saturation. The efficiency of fluorescence lifetime imaging microscopy setups is connected to the speed of acquisition and thus to the imaging throughput. We report on the optimal conditions for balancing signal-to-noise ratio and acquisition speed in fluorescence lifetime sensing. © 2007 Optical Society of America.},
note = {cited By (since 1996) 17},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@conference{Palero2007,
title = {Spectrally-resolved multiphoton imaging of post-mortem biopsy and in-vivo mouse skin tissues},
author = {Jonathan A. Palero and Henriëtte S. de Bruijn and Angélique van der Ploeg - van den Heuvel and Henricus J.C.M. Sterenborg and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-34548256238&partnerID=40&md5=0817ae1da6b80511a80170846c134b8c},
year  = {2007},
date = {2007-01-01},
journal = {Progress in Biomedical Optics and Imaging - Proceedings of SPIE},
volume = {6442},
abstract = {The deep-tissue penetration and submicron spatial resolution of multi-photon microscopy and the high-detection efficiency and nanometer spectral resolution capability of a spectrograph were combined to study the intrinsic emission of mouse skin post mortem biopsy and section, and in vivo tissue samples. The different layers of skin could be clearly distinguished based on both their spectral signature and morphology. Auto fluorescence could be detected from both cellular and extra cellular structures. In addition SHG from collagen and a narrowband spectral emission band related to collagen were observed. Visualization of the spectral images in RGB color allowed us to identify tissue structures such as epidermal cells, lipid-rich keratinocytes and intercellular structures, hair follicles, collagen, elastin, and dermal fibroblasts. The results also showed morphological and spectral differences between the mouse skin post mortem biopsy and in vivo samples which explained by biochemical differences, specifically of NAD(P)H. Overall, spectral imaging provided a wealth of information not easily obtainable with present conventional multi-photon imaging methods.},
note = {cited By (since 1996) 0},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@article{Palero2007992,
title = {Spectrally resolved multiphoton imaging of in vivo and excised mouse skin tissues},
author = {Jonathan A. Palero and Henriëtte S. de Bruijn and Angélique van der Ploeg - van den Heuvel and Henricus J.C.M. Sterenborg and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-34547697287&partnerID=40&md5=dbe7c67d0103cef6a6c9359651c58bd5},
year  = {2007},
date = {2007-01-01},
journal = {Biophysical Journal},
volume = {93},
number = {3},
pages = {992-1007},
abstract = {The deep tissue penetration and submicron spatial resolution of multiphoton microscopy and the high detection efficiency and nanometer spectral resolution of a spectrograph were utilized to record spectral images of the intrinsic emission of mouse skin tissues. Autofluorescence from both cellular and extracellular structures, second-harmonic signal from collagen, and a narrowband emission related to Raman scattering of collagen were detected. Visualization of the spectral images by wavelength-to-RGB color image conversion allowed us to identify and discriminate tissue structures such as epidermal keratinocytes, lipid-rich corneocytes, intercellular structures, hair follicles, collagen, elastin, and dermal cells. Our results also showed morphological and spectral differences between excised tissue section, thick excised tissue, and in vivo tissue samples of mouse skin. Results on collagen excitation at different wavelengths suggested that the origin of the narrowband emission was collagen Raman peaks. Moreover, the oscillating spectral dependency of the collagen second-harmonic intensity was experimentally studied. Overall, spectral imaging provided a wealth of information not easily obtainable with present conventional multiphoton imaging systems. © 2007 by the Biophysical Society.},
note = {cited By (since 1996) 64},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Bader20076934,
title = {Imaging of protein cluster sizes by means of confocal time-gated fluorescence anisotropy microscopy},
author = {Arjen N. Bader and Erik G. Hofman and Paul M.P. van Bergen en Henegouwen and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-34249674419&partnerID=40&md5=def4ebb4cf2f93d47d731f6997214266},
year  = {2007},
date = {2007-01-01},
journal = {Optics Express},
volume = {15},
number = {11},
pages = {6934-6945},
abstract = {A time-resolved fluorescence anisotropy imaging method for studying nanoscale clustering of proteins or lipids was developed and evaluated. It is based on FRET between the identical fluorophores (homo-FRET), which results in a rapid depolarization of the fluorescence. The method employs the time-resolved fluorescence anisotropy decays recorded in a confocal microscope equipped with pulsed excitation and time-gated detection. From the decay the limiting anisotropy ninf was derived, which is a direct measure for the number of fluorophores per cluster. The method was evaluated by imaging GPI-GFP, a lipid raft marker. Small clusters were observed in the plasma membrane while the cytoplasm and the Golgi contained predominantly monomers. © 2007 Optical Society of America.},
note = {cited By (since 1996) 23},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@conference{Bader2007,
title = {Confocal time-resolved fluorescence anisotropy imaging},
author = {Arjen N. Bader and Erik G. Hofman and Paul M.P. van Bergen en Henegouwen and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-34247352939&partnerID=40&md5=7fd6104afec912e69d29c5b69218c832},
year  = {2007},
date = {2007-01-01},
journal = {Progress in Biomedical Optics and Imaging - Proceedings of SPIE},
volume = {6441},
abstract = {A confocal time-resolved fluorescence anisotropy imaging set-up is presented. It combines a confocal laser scanning microscope equipped with a pulsed laser and two time gated detection systems with 4 gates each (LiMo, originally developed for FLIM). The anisotropy decays obtained with the time gating system yield results that compare well with the high time-resolution (non-imaging) decays recorded using Time Correlated Single Photon Counting. Time resolved anisotropy imaging experiments on cells expressing GPI-GFP were carried out. Clear distinction could be made between the anisotropy in the plasma membrane and in the interior of the cell.},
note = {cited By (since 1996) 2},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@article{Kremers20073775,
title = {Improved green and blue fluorescent proteins for expression in bacteria and mammalian cells},
author = {Gert Jan Kremers and Joachim Goedhart and Dave J. van den Heuvel and Hans C. Gerritsen and Theodorus W.J. Gadella},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-33947704150&partnerID=40&md5=29c124713c0d41b7e009e91af27b7bb8},
year  = {2007},
date = {2007-01-01},
journal = {Biochemistry},
volume = {46},
number = {12},
pages = {3775-3783},
abstract = {Fluorescent proteins have become an invaluable tool in cell biology. The green fluorescent protein variant EGFP is especially widely applied. Use of fluorescent proteins, including EGFP, however can be hindered by inefficient protein folding, resulting in protein aggregation and reduced fluorescence. This is especially profound in prokaryotic cells. Furthermore, EBFP, a blue fluorescent variant of EGFP, is rarely used because of its dim fluorescence and fast photobleaching. Thus, efforts to improve properties such as protein folding, fluorescence brightness, and photostability are important. Strongly enhanced green fluorescent (SGFP2) and strongly enhanced blue fluorescent (SBFP2) proteins were created, based on EGFP and EBFP, respectively. We used site-directed mutagenesis to introduce several mutations, which were recently shown to improve the fluorescent proteins EYFP and ECFP. SGFP2 and SBFP2 exhibit faster and more efficient protein folding and accelerated chromophore oxidation in vitro. For both strongly enhanced fluorescent proteins, the photostability was improved 2-fold and the quantum yield of SBFP2 was increased 3-fold. The improved folding efficiency reduced the extent of protein aggregation in Escherichia coli, thereby increasing the brightness of bacteria expressing SGFP2 7-fold compared to the brightness of those expressing EGFP. Bacteria expressing SBFP2 were 16-fold more fluorescent than those expressing EBFP. In mammalian cells, the improvements were less pronounced. Cells expressing SGFP2 were 1.7-fold brighter than those expressing EGFP, which was apparently due to more efficient protein expression and/or chromophore maturation. Mammalian cells expressing SBFP2 were 3.7-fold brighter than cells expressing EBFP. This increase in brightness closely resembled the increase in intrinsic brightness observed for the purified recombinant protein. The increased maturation efficiency and photostability of SGFP2 and SBFP2 facilitate detection and extend the maximum duration of fluorescence imaging. © 2007 American Chemical Society.},
note = {cited By (since 1996) 37},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@conference{Chen2007,
title = {Stretching sub-micron DNA fragments with optical tweezers},
author = {Yi Fan Chen and Gerhard A. Blab and Jens Christian Meiners},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-42149116216&partnerID=40&md5=0bd4b8863d00565d9aa2132db1af6cf9},
doi = {10.1117/12.736824},
year  = {2007},
date = {2007-01-01},
journal = {Proceedings of SPIE - The International Society for Optical Engineering},
volume = {6644},
note = {cited By 1},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@article{Lasne200714184,
title = {Label-free optical imaging of mitochondria in live cells},
author = {David Lasne and Gerhard A. Blab and Francesca A. de Giorgi and François Ichas and Brahim Lounis and Laurent Cognet},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-35349030875&partnerID=40&md5=630b4a8552ceebe01da4300cad109243},
doi = {10.1364/OE.15.014184},
year  = {2007},
date = {2007-01-01},
journal = {Optics Express},
volume = {15},
number = {21},
pages = {14184-14193},
note = {cited By 38},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{VanVugt2006,
title = {Exciton polaritons confined in a ZnO nanowire cavity},
author = {Lambert K. van Vugt and Sven Rühle and Prasanth Ravindran and Hans C. Gerritsen and L. Kobus Kuipers and Daniel A.M. Vanmaekelbergh},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-33749500751&partnerID=40&md5=7d85c89fbe1f7ee3210bf0f25d0e266d},
year  = {2006},
date = {2006-01-01},
journal = {Physical Review Letters},
volume = {97},
number = {14},
abstract = {Semiconductor nanowires of high purity and crystallinity hold promise as building blocks for miniaturized optoelectrical devices. Using scanning-excitation single-wire emission spectroscopy, with either a laser or an electron beam as a spatially resolved excitation source, we observe standing-wave exciton polaritons in ZnO nanowires at room temperature. The Rabi splitting between the polariton branches is more than 100Â meV. The dispersion curve of the modes in the nanowire is substantially modified due to light-matter interaction. This finding forms a key aspect in understanding subwavelength guiding in these nanowires. © 2006 The American Physical Society.},
note = {cited By (since 1996) 80},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@conference{Palero2006,
title = {Three-dimensional multiphoton autofluorescence spectral imaging of live tissues},
author = {Jonathan A. Palero and Henriëtte S. de Bruijn and Angélique van der Ploeg - van den Heuvel and Henricus J.C.M. Sterenborg and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-33745134709&partnerID=40&md5=12ecc1acd47dcd9005825cc103563f88},
year  = {2006},
date = {2006-01-01},
journal = {Progress in Biomedical Optics and Imaging - Proceedings of SPIE},
volume = {6191},
abstract = {We combined a homebuilt multiphoton microscope and a prism-CCD based spectrograph to develop a spectral imaging system capable of imaging deep into live tissues. The spectral images originate from the two-photon autofluorescence of the tissue and second harmonic signal from the collagen fibers. A highly penetrating near-infrared light is used to excite the endogenous fluorophores via multiphoton excitation enabling us to produce high quality images deep into the tissue. We were able to produce 100-channel (330 nm to 600 nm) autofluorescence spectral images of live skin tissues in less than 2 minutes for each xy-section. The spectral images rendered in RGB (real) colors showed green hair shafts, blue cells, and purple collagen. Analysis on the optical signal degradation with increasing depth of the collagen second-harmonic signal showed 1) exponential decay behavior of the intensity and 2) linear broadening of the spectrum. This spectral imaging system is a promising tool for both in biological applications and biomedical applications such as optical biopsy.},
note = {cited By (since 1996) 0},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@conference{Palero2006b,
title = {In vivo intrinsic emission spectral imaging microscopy of mouse skin tissues},
author = {Jonathan A. Palero and Henriëtte S. de Bruijn and Angélique van der Ploeg - van den Heuvel and Henricus J.C.M. Sterenborg and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-33646179814&partnerID=40&md5=b086f89a39e3ec134c51899c599c180e},
year  = {2006},
date = {2006-01-01},
journal = {Proceedings of SPIE - The International Society for Optical Engineering},
volume = {6089},
abstract = {Interest in the development of optical technologies that have the capability of performing in situ tissue diagnosis without the need for surgical biopsy and processing has been growing. In general, optical diagnostic techniques can be classified into two categories: (1) spectroscopic diagnostics and (2) optical imaging. Spectroscopic diagnostic techniques are used to obtain an entire spectrum of a single tissue site (point-measurement method). On the other hand, optical imaging methods are aimed at recording a two- or three-dimensional image of a sample region. A third category, which combines the two modalities, is currently in an early development phase. This category, referred to as spectral imaging, has been applied to cytomics, fluorescence resonance energy transfer (FRET) analysis, histology, fluorescence microscopy and autofluorescence microscopy. In this study, we combined a multi-photon microscope with a sensitive prism-based spectrograph and employed it for intrinsic emission spectral imaging microscopy of in vivo mouse skin tissues. We show results on: (1) spectral image RGB real-color visualization; (2) tissue layer discrimination using spectral signatures; (3) depth-resolved skin tissue spectral imaging; and (4) tissue component determination by spectral (linear) unmixing.},
note = {cited By (since 1996) 0},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@conference{Palero2006b,
title = {Two-photon spectral imaging microscopy of skin tissues},
author = {Jonathan A. Palero and Henriëtte S. de Bruijn and Henricus J.C.M. Sterenborg and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-33646165265&partnerID=40&md5=6fda343dea1d6b0c21bc9321188191b8},
year  = {2006},
date = {2006-01-01},
journal = {Proceedings of SPIE - The International Society for Optical Engineering},
volume = {6089},
abstract = {The last two decades saw the emergence of spectroscopy and microscopic imaging as techniques for tissue diagnostics. The biochemical state of the tissue is revealed by spectroscopy, while the morphological information is visualized by microscopic imaging. Little research has been carried out to diagnose tissues based on the combination of spectroscopy and microscopic imaging. Here, we report on tissue spectroscopy and microscopic imaging employing two-photon excitation of tissue autofluorescence and second harmonic generation. We designed and constructed a prism-based spectral imaging system coupled to a two-photon microscope. Full emission spectra with a 1-7 nm spectral resolution covering 330nm to 600nm can be recorded at a maximum rate of 500 spectra per second equivalent to about 0.5 frames/min (224×224 pixels). We present results on spectral imaging of human skin sections and in-depth imaging of pig skin tissue. Different skin layers show clear differences in their intrinsic emission spectral signature that can be used for diagnosis.},
note = {cited By (since 1996) 0},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@conference{Palero2006b,
title = {Photonic crystal fiber as a tunable light source for visible wavelength two-photon microscopy},
author = {Jonathan A. Palero and Vincent O. Boer and Jacob C. Vijverberg and Henricus J.C.M. Sterenborg and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-33646202114&partnerID=40&md5=273b24c33257648401e104aa0b36183d},
year  = {2006},
date = {2006-01-01},
journal = {Proceedings of SPIE - The International Society for Optical Engineering},
volume = {6089},
abstract = {Two-photon microscopy revolutionized deep and live tissue imaging. It uses near-infrared femtosecond-pulsed laser sources, usually Ti:Sa lasers, to excite fluorescence. Several endogenous and synthetic fluorophores are, however, excited with wavelengths shorter than 360 nm, including NADH, tryptophan and the ratiometric Ca 2+ indicators. Efficient two-photon excitation imaging of these endogenous fluorophores is difficult at present due to the lack of suitable laser sources. To address these concerns, we investigated the use of photonic crystal fibers as a laser source for visible wavelength two-photon microscopy. The high nonlinearity of the photonic crystal fibers leads to supercontinuum generation that can span the visible to the near-infrared spectral regions. We investigated the spectral and temporal properties of photonic crystal fibers excited by a near-infrared femtosecond Ti:Sa laser. Our results show that the fiber emission can be tuned by variation of laser excitation wavelength and laser intensity. Our autocorrelation measurements show that the pulse duration of the PCF nonsolitonic radiation is in the order of a few picoseconds. We also demonstrate the application of the photonic crystal fiber output to two-photon microscopy of tryptophan.},
note = {cited By (since 1996) 0},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@article{Esposito2006,
title = {Innovating lifetime microscopy: A compact and simple tool for life sciences, screening, and diagnostics},
author = {Alessandro Esposito and Hans C. Gerritsen and Thierry Oggier and Felix Lustenberger and Fred S. Wouters},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-33748468432&partnerID=40&md5=63ead6cdea4e7997f85973629c778e62},
year  = {2006},
date = {2006-01-01},
journal = {Journal of Biomedical Optics},
volume = {11},
number = {3},
abstract = {Fluorescence lifetime imaging microscopy (FLIM) allows the investigation of the physicochemical environment of fluoro-chromes and protein-protein interaction mapping by Förster resonance energy transtfer (FRET) in living cels. However, simpler and cheaper solutions are required before this powerful analytical technique finds a broader application in the life science. Wide-field frequency-domain FLIM represents a solution whose application is currently limited by the need for multichannel-plate image intensifiers. We recently showed the feasibility of using a charge-coupled device/complementory metal-oxide semiconductor (CCD/CMOS) hybrid lock-in imager, originally developed for 3-D vision, as an add-on device for lifetime measurements on existing wide-field microscopes. In the present work, the performance of the setup is validated by comparison with well-established wide-field frequency-domain FLIM measurements. Furthermore, we combine the lock-in imager with solid-state light sources. This results in a simple, inexpensive, and compact FLIM system, operating at a video rate and capable of single-shot acquisition by virtue of the unique parallel retrieval of two phase-dependent images. This novel FLIM setup is used for cellular and FRET imaging, and for high-throughput and fast imaging applications. The all-solid-state design bridges the technological gap that limits the use of FLIM in areas such as drug discovery and medical diagnostics. © 2006 Society of Photo-Optical Instrumentation Engineers.},
note = {cited By (since 1996) 22},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Palero20064395,
title = {In vivo nonlinear spectral imaging in mouse skin},
author = {Jonathan A. Palero and Henriëtte S. de Bruijn and Angélique van der Ploeg - van den Heuvel and Henricus J.C.M. Sterenborg and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-33646551193&partnerID=40&md5=1fb9a6451c23e09591f4d01d522465c8},
year  = {2006},
date = {2006-01-01},
journal = {Optics Express},
volume = {14},
number = {10},
pages = {4395-4402},
abstract = {We report on two-photon autofluorescence and second harmonic spectral imaging of live mouse tissues. The use of a high sensitivity detector and ultraviolet optics allowed us to record razor-sharp deep-tissue spectral images of weak autofluorescence and short-wavelength second harmonic generation by mouse skin. Real-color image representation combined with depth-resolved spectral analysis enabled us to identify tissue structures. The results show that linking nonlinear deep-tissue imaging microscopy with autofluorescence spectroscopy has the potential to provide important information for the diagnosis of skin tissues. © 2006 Optical Society of America.},
note = {cited By (since 1996) 48},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Prasanth2006,
title = {Resonance enhancement of optical second harmonic generation in a ZnO nanowire},
author = {Prasanth Ravindran and Lambert K. van Vugt and Daniel A.M. Vanmaekelbergh and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-33646508587&partnerID=40&md5=ec62b27f06128fb8c32eaf34f14fead7},
year  = {2006},
date = {2006-01-01},
journal = {Applied Physics Letters},
volume = {88},
number = {18},
abstract = {Two-photon absorption measurement has been carried out in a single 80 nm×10 μm ZnO nanowire using femtosecond laser pulses in the wavelength range of 700-800 nm. In addition to the deep-level green emission around 530 nm due to surface defects and the near band-edge ultraviolet emission around 360 nm due to the exciton, a second harmonic peak has been observed. The strength of the frequency-doubled component is found to enhance while the two-photon absorption wavelength is tuned towards the exciton wavelength of the nanowire. This behavior can be ascribed to the resonant exciton absorption in ZnO nanowires. © 2006 American Institute of Physics.},
note = {cited By (since 1996) 33},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Tovmachenko200691,
title = {Fluorescence enhancement by metal-core/silica-shell nanoparticles},
author = {Oleg G. Tovmachenko and Christina M. Graf and Dave J. van den Heuvel and Alfons van Blaaderen and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-30444437914&partnerID=40&md5=886e6b587381e38adba544aea77c6d91},
year  = {2006},
date = {2006-01-01},
journal = {Advanced Materials},
volume = {18},
number = {1},
pages = {91-95},
abstract = {The enhancement of fluorescence by nanoparticles consisting of a metal core, a silica-spacer shell, and a dye-labeled shell, are observed. Fluorescence enhancement is expressed in terms of apparent quantum yield, the ratio of number of emitted photons in the presence of enhancement, and the number of absorbed photons in the absence of enhancement. The important factors that affect fluorescence enhancement are size and shape of nanoparticles, the orientation of dye dipole moments, the overlap of the absorption and emission bands of the dye and, the radiative decay and quantum yield of fluorescent molecules. Fluorescence enhancement results in shortening of excited-state lifetime thus improving the photostability of the dye.},
note = {cited By (since 1996) 133},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Lasne20064598,
title = {Single Nanoparticle Photothermal Tracking (SNaPT) of 5-nm gold beads in live cells},
author = {David Lasne and Gerhard A. Blab and Stéphane Berciaud and Martin Heine and Laurent Groc and Daniel Choquet and Laurent Cognet and Brahim Lounis},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-33845383320&partnerID=40&md5=0183c24ef26a6d6a86b19f50f95e4c63},
doi = {10.1529/biophysj.106.089771},
year  = {2006},
date = {2006-01-01},
journal = {Biophysical Journal},
volume = {91},
number = {12},
pages = {4598-4604},
note = {cited By 153},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@conference{Berciaud2006,
title = {Photothermal absorption spectroscopy of individual gold nanoparticles and CdSe/ZnS semiconductor nanocrystals},
author = {Stéphane Berciaud and Laurent Cognet and David Lasne and Gerhard A. Blab and Brahim Lounis},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-55649104957&partnerID=40&md5=5804587a7f0a5eef9f85bfb23de3a3c0},
doi = {10.1109/CLEO.2006.4629092},
year  = {2006},
date = {2006-01-01},
journal = {Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference, CLEO/QELS 2006},
note = {cited By 0},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@conference{Berciaud2006b,
title = {Absorption spectroscopy of individual nano-objects and improved readout of DNA microarrays using photothermal detection},
author = {Stéphane Berciaud and Laurent Cognet and Gerhard A. Blab and David Lasne and Josè A. Remacle and Philippe H. Tamarat and Brahim Lounis},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-33745316055&partnerID=40&md5=2b452541ce0988f256da4fb10604bfbf},
doi = {10.1117/12.647808},
year  = {2006},
date = {2006-01-01},
journal = {Progress in Biomedical Optics and Imaging - Proceedings of SPIE},
volume = {6092},
note = {cited By 0},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@conference{Lasne2006,
title = {Single molecule, CdSe/ZnS quantum dot and gold nanoparticle detection in live neurons},
author = {David Lasne and Laurent Cognet and Stéphane Berciaud and Gerhard A. Blab and Laurent Groc and Martin Heine and Daniel Choquet and Brahim Lounis},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-33745202849&partnerID=40&md5=4dea9a849417c1a9ebccaf361f93564d},
doi = {10.1117/12.647788},
year  = {2006},
date = {2006-01-01},
journal = {Progress in Biomedical Optics and Imaging - Proceedings of SPIE},
volume = {6096},
note = {cited By 0},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@article{Berciaud2006b,
title = {Photothermal heterodyne imaging of individual metallic nanoparticles: Theory versus experiment},
author = {Stéphane Berciaud and David Lasne and Gerhard A. Blab and Laurent Cognet and Brahim Lounis},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-33144468896&partnerID=40&md5=b635d9c34171870a3b7f93b62e725168},
doi = {10.1103/PhysRevB.73.045424},
year  = {2006},
date = {2006-01-01},
journal = {Physical Review B - Condensed Matter and Materials Physics},
volume = {73},
number = {4},
note = {cited By 112},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Blab2006L13,
title = {Optical readout of gold nanoparticle-based DNA microarrays without silver enhancement},
author = {Gerhard A. Blab and Laurent Cognet and Stéphane Berciaud and Isabelle Alexandre and Dieter Husar and Josè A. Remacle and Brahim Lounis},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-33646148710&partnerID=40&md5=f9cf30b08231721eec091e0c0245ea00},
doi = {10.1529/biophysj.105.076182},
year  = {2006},
date = {2006-01-01},
journal = {Biophysical Journal},
volume = {90},
number = {1},
pages = {L13-L15},
note = {cited By 38},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Esposito20054286,
title = {Fluorescence lifetime heterogeneity resolution in the frequency domain by lifetime moments analysis},
author = {Alessandro Esposito and Hans C. Gerritsen and Fred S. Wouters},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-28444451587&partnerID=40&md5=d8e9175af3240cec66396a45494bd4cc},
year  = {2005},
date = {2005-01-01},
journal = {Biophysical Journal},
volume = {89},
number = {6},
pages = {4286-4299},
abstract = {Fluorescence lifetime imaging microscopy presents a powerful tool in biology and biophysics because it allows the investigation of the local environment of a fluorochrome in living cells in a quantitative manner. Furthermore, imaging Förster-type resonance energy transfer (FRET) by fluorescence lifetime imaging microscopy enables protein-protein interactions and intermolecular distances to be mapped under physiological conditions. Quantitative and precise data analysis methods are required to access the richness of information that is contained in FRET data on biological samples. Lifetime detection in the frequency-domain yields two lifetime estimations. The lifetime moments analysis (LiMA) provides a quantitative measure of the lifetime distribution broadness by exploiting the analytical relationship between the phase- and demodulation-lifetime estimations and relating them to the weighted average and variance of the lifetime distribution. The LiMA theoretical framework is validated by comparison with global analysis and by applying it to a constrained two-component FRET system using simulations and experiments. Furthermore, a novel LIMA-based error analysis and a more intuitive formalism for global analysis are presented. Finally, a new method to resolve a FRET system is proposed and experimentally applied to the investigation of protein-protein interactions. © 2005 by the Biophysical Society.},
note = {cited By (since 1996) 34},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@conference{Prasanth200531,
title = {Two-photon absorption and resonance enhancement of second harmonic in ZnO nanowires},
author = {Prasanth Ravindran and Lambert K. van Vugt and Jonathan A. Palero and Hans C. Gerritsen and Daniel A.M. Vanmaekelbergh},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-33746923498&partnerID=40&md5=a6fcc852144b5995bab653358bf35db3},
year  = {2005},
date = {2005-01-01},
journal = {2005 5th IEEE Conference on Nanotechnology},
volume = {2},
pages = {31-34},
note = {cited By (since 1996) 0},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@conference{Palero2005,
title = {Non-liniear microscopy and spectroscopy of skin tissues},
author = {Jonathan A. Palero and Gwendal Latouche and Henriëtte S. de Bruijn and Hans C. Gerritsen and Henricus J.C.M. Sterenborg},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-33244457410&partnerID=40&md5=c7d1a17b5230824b7e79a598a2802d88},
year  = {2005},
date = {2005-01-01},
journal = {Progress in Biomedical Optics and Imaging - Proceedings of SPIE},
volume = {5968},
abstract = {We combined a non-linear microscope with a sensitive prism-based spectrograph and employed it for the imaging of the auto fluorescence of skin tissues. The system has a sub-micron spatial resolution and a spectral resolution of better than 5 nm. The spectral images contain signals arising from two-photon excited fluorescence (TPEF) of endogenous fluorophores in the skin and from second harmonic generation (SHG) produced by the collagen fibers, which have non-centrosymmetric structure. Non-linear microscopy has the potential to image deep into optically thick specimens because it uses near-infrared (NIR) laser excitation. In addition, the phototoxicity of the technique is comparatively low. Here, the technique is used for the spectral imaging of unstained skin tissue sections. We were able to image weak cellular autofluorescence as well as strong collagen SHG. The images were analyzed by spectral unmixing and the results exhibit a clear spectral signature for the different skin layers.},
note = {cited By (since 1996) 0},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@article{Esposito20059812,
title = {All-solid-state lock-in imaging for wide-field fluorescence lifetime sensing},
author = {Alessandro Esposito and Hans C. Gerritsen and Thierry Oggier and Felix Lustenberger and Fred S. Wouters},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-28044464903&partnerID=40&md5=28e15893c0b0e9e646028e8d7aebcd64},
year  = {2005},
date = {2005-01-01},
journal = {Optics Express},
volume = {13},
number = {24},
pages = {9812-9821},
abstract = {Fluorescence Lifetime Imaging Microscopy (FLIM) is a powerful technique that is increasingly being used in the life sciences during the past decades. However, a broader application of FLIM requires more cost-effective and user-friendly solutions. We demonstrate the use of a simple CCD/CMOS lock-in imager for fluorescence lifetime detection. The SwissRanger SR-2 time-of-flight detector, originally developed for 3D vision, embeds all the functionalities required for FLIM in a compact system. The further development of this technology and its combination with light-emitting- and laser diodes could drive a wider spreading of the use of FLIM including high-throughput applications. ©2005 Optical Society of America.},
note = {cited By (since 1996) 18},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Palero20055363,
title = {Short-wavelength two-photon excitation fluorescence microscopy of tryptophan with a photonic crystal fiber based light source},
author = {Jonathan A. Palero and Vincent O. Boer and Jacob C. Vijverberg and Hans C. Gerritsen and Henricus J.C.M. Sterenborg},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-22744450093&partnerID=40&md5=7a168be98d6e4d67cae96f34c1690bd0},
year  = {2005},
date = {2005-01-01},
journal = {Optics Express},
volume = {13},
number = {14},
pages = {5363-5368},
abstract = {We report on a novel and simple light source for short-wavelength two-photon excitation fluorescence microscopy based on the visible nonsolitonic radiation from a photonic crystal fiber. We demonstrate tunability of the light source by varying the wavelength and intensity of the Ti:Sapphire excitation light source. The visible nonsolitonic radiation is used as an excitation light source for two-photon fluorescence microscopy of tryptophan powder. © 2005 Optical Society of America.},
note = {cited By (since 1996) 27},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@conference{Berciaud20051,
title = {Optical detection and spectroscopy of single metal nanoparticles},
author = {Stéphane Berciaud and David Lasne and Gerhard A. Blab and Philippe H. Tamarat and Laurent Cognet and Brahim Lounis},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-31844456999&partnerID=40&md5=7e96eded244ae9fb3f563263ba912f1a},
doi = {10.1117/12.621174},
year  = {2005},
date = {2005-01-01},
journal = {Proceedings of SPIE - The International Society for Optical Engineering},
volume = {5927},
pages = {1-13},
note = {cited By 1},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@conference{Berciaud2005344,
title = {Photothermal heterodyne imaging and absorption spectroscopy of individual nonfluorescent nano-objects},
author = {Stéphane Berciaud and David Lasne and Gerhard A. Blab and Philippe H. Tamarat and Laurent Cognet and Brahim Lounis},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-33847263035&partnerID=40&md5=67d066e8d52d6787f568f76b65e92727},
doi = {10.1109/EQEC.2005.1567509},
year  = {2005},
date = {2005-01-01},
journal = {2005 European Quantum Electronics Conference, EQEC '05},
volume = {2005},
pages = {344},
note = {cited By 0},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@conference{Berciaud2005109,
title = {Photothermal heterodyne imaging and spectroscopy of individual metal nanoparticles},
author = {Stéphane Berciaud and Laurent Cognet and Gerhard A. Blab and Brahim Lounis},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-27144437896&partnerID=40&md5=7fd510082a5f90bafe0f3e0ca0f5986e},
year  = {2005},
date = {2005-01-01},
journal = {Quantum Electronics and Laser Science Conference (QELS)},
volume = {1},
pages = {109-111},
note = {cited By 0},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@article{Agronskaia20041230,
title = {Fast fluorescence lifetime imaging of calcium in living cells},
author = {Alexandra V. Agronskaia and Leon G.J. Tertoolen and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-12844250795&partnerID=40&md5=5924f55906c8f8c79c5e7c8ad692d377},
year  = {2004},
date = {2004-01-01},
journal = {Journal of Biomedical Optics},
volume = {9},
number = {6},
pages = {1230-1237},
abstract = {A fast fluorescence lifetime imaging (FLIM) system is developed that can acquire images at a rate of hundreds of frames per second. The FLIM system is based on a wide-field microscope equipped with a time-gated intensified CCD detector and a pulsed laser. The time-gated detector acquires the signals from two time gates simultaneously and is therefore insensitive to movements of the specimen and photo-bleaching. The system is well suited for quantitative biological FLIM experiments and its performance is evaluated in calcium imaging experiments on beating neonatal rat myocytes. Several calcium sensitive dyes are characterized and tested for their suitability for fast FLIM experiments: Oregon Green Bapta-1 (OGB1), Oregon Green Bapta-2 (OGB2), and Oregon Green Bapta-5N (OGB5N). Overall the sensitivity range of these dyes is shifted to low calcium concentrations when used as lifetime dyes. OGB1 and OGB2 behave very similarly and can be used for FLIM-based calcium imaging in the range 1 to ∼500 nM and OGB5N can be used up to 3 μM. The fast FLIM experiments on the myocytes could be carried out at a 100-Hz frame rate. During the beating of the myocytes a lifetime change of about 20% is observed. From the lifetime images a rest calcium level of about 65 nM is found. © 2004 Society of Photo-Optical Instrumentation Engineers.},
note = {cited By (since 1996) 45},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@conference{Gerritsen200477,
title = {High-speed fluorescence lifetime imaging},
author = {Hans C. Gerritsen and Dave J. van den Heuvel and Alexandra V. Agronskaia},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-5644230951&partnerID=40&md5=28b89b231423ae22c452be97e4cdc301},
year  = {2004},
date = {2004-01-01},
journal = {Proceedings of SPIE - The International Society for Optical Engineering},
volume = {5323},
pages = {77-87},
abstract = {In Fluorescence Lifetime Imaging (FLIM) the ns fluorescence decay is used for imaging. It yields information about the local environment of the fluorescent molecule and is very well suited for quantitative imaging. FLIM was introduced more than one decade ago now. Most of the implementations of FLIM require comparatively long acquisition times on the order of ten seconds or more. This hampers the use of FLIM for the study of dynamic processes. In FLIM at least one order of magnitude more signal is required than in conventional intensity imaging. Therefore, fast FLIM acquisition rates require efficient detection schemes and detectors. We evaluated the count rate limitation in time gated and TCSPC FLIM of a number of single photon counting detectors. In particular we looked at the performance of a conventional fast head-on PMT (R1894), a GaAs photocathode PMT (H7422P-40) and a single photon counting avalanche photo diode (SPCM-AQR14). The high quantum efficiency GaAs photocathode PMT and avalanche photo diode detectors show lifetime shifts in both time gated detection and in TCSPC starting at a detection count rate of 1 - 2 MHz. The conventional PMT shows lifetime shifts starting at a detection count rate of about 2.5 MHz in TCSPC and at about 6 MHz for the time gated detection system. The detection efficiency of the TCSPC based system goes down rapidly above about 1 MHz due to the dead time of the detection electronics. The time gated detection system shows little or no reduction of the detection efficiency up to detection count rates of 10 MHz with the conventional fast PMT. The time gated-detection system was coupled to a multi-photon excitation microscope. Calcium transients were recorded in cardiac rat myocytes at a 1 Hz frame rate. The system operated at the full repetition rate of the Ti:Sa laser. Here, the frame rate was limited by the maximum count rate of the PMT.},
note = {cited By (since 1996) 6},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@article{Berciaud2004,
title = {Photothermal heterodyne imaging of individual nonfluorescent nanoclusters and nanocrystals},
author = {Stéphane Berciaud and Laurent Cognet and Gerhard A. Blab and Brahim Lounis},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-42749100048&partnerID=40&md5=881dcfe9b3232277b6df3d1281369128},
doi = {10.1103/PhysRevLett.93.257402},
year  = {2004},
date = {2004-01-01},
journal = {Physical Review Letters},
volume = {93},
number = {25},
note = {cited By 177},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Blab2004727,
title = {Simultaneous wide-field imaging and spectroscopy of localized fluorophores},
author = {Gerhard A. Blab and Silke Oellerich and Reinier Schumm and Thomas Schmidt},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-1942486849&partnerID=40&md5=0d179bab8c8b01a04ed877c9aca62b97},
doi = {10.1364/OL.29.000727},
year  = {2004},
date = {2004-01-01},
journal = {Optics Letters},
volume = {29},
number = {7},
pages = {727-729},
note = {cited By 9},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Blab2004495,
title = {Homogeneous Detection of Single Rolling Circle Replication Products},
author = {Gerhard A. Blab and Thomas Schmidt and Mats F. Nilsson},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0347128038&partnerID=40&md5=22d265eb0259549def245ec0d28c26a6},
doi = {10.1021/ac034987+},
year  = {2004},
date = {2004-01-01},
journal = {Analytical Chemistry},
volume = {76},
number = {2},
pages = {495-498},
note = {cited By 49},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Lommerse2004609,
title = {Single-Molecule Imaging of the H-Ras Membrane-Anchor Reveals Domains in the Cytoplasmic Leaflet of the Cell Membrane},
author = {Piet H.M. Lommerse and Gerhard A. Blab and Laurent Cognet and Gregory S. Harms and Bogusława E. Snaar-Jagalska and Herman P. Spaink and Thomas Schmidt},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0346057912&partnerID=40&md5=ddeb5e2b0c00cb85ce1f95fce31a2d6b},
year  = {2004},
date = {2004-01-01},
journal = {Biophysical Journal},
volume = {86},
number = {1 I},
pages = {609-616},
note = {cited By 104},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Agronskaia20031655,
title = {High frame rate fluorescence lifetime imaging},
author = {Alexandra V. Agronskaia and Leon G.J. Tertoolen and Hans C. Gerritsen},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0042199004&partnerID=40&md5=03931c8c86f9418eeb8b741c8e77c571},
year  = {2003},
date = {2003-01-01},
journal = {Journal of Physics D: Applied Physics},
volume = {36},
number = {14},
pages = {1655-1662},
abstract = {A fast time-domain based fluorescence lifetime imaging (FLIM) microscope is presented that can operate at frame rates of hundreds of frames per second. A beam splitter in the detection path of a wide-field fluorescence microscope divides the fluorescence in two parts. One part is optically delayed with respect to the other. Both parts are viewed with a single time-gated intensified CCD camera with a gate width of 5 ns. The fluorescence lifetime image is obtained from the ratio of these two images. The fluorescence lifetime resolution of the FLIM microscope is verified both with dye solutions and fluorescent latex beads. The fluorescence lifetimes obtained from the reference specimens are in good agreement with values obtained from time correlated single photon counting measurements on the same specimens. The acquisition speed of the FLIM system is evaluated with a measurement of the calcium fluxes in neonatal rat myocytes stained with the calcium probe Oregon Green 488-Bapta. Fluorescence lifetime images of the calcium fluxes related to the beating of the myocytes are acquired with frame rates of up to 100 Hz.},
note = {cited By (since 1996) 43},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Centonze2003542,
title = {Fluorescence resonance energy transfer imaging microscopy},
author = {Victoria E. Centonze and Mao Sun and Atsushi Masuda and Hans C. Gerritsen and Brian A. Herman},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-12244280825&partnerID=40&md5=cf7604b51b390b38ea092b35cadaa64b},
year  = {2003},
date = {2003-01-01},
journal = {Methods in Enzymology},
volume = {360},
pages = {542-560},
note = {cited By (since 1996) 29},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{VanSark2002871,
title = {Blueing, bleaching, and blinking of single CdSe/ZnS quantum dots},
author = {Wilfried G.J.H.M. van Sark and Patrick L.T.M.Frederix and Ageeth A. Bol and Hans C. Gerritsen and Andries Meijerink},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0037131429&partnerID=40&md5=9c8dd1ff8bad5904ef8c5c7e8bd400b1},
year  = {2002},
date = {2002-01-01},
journal = {ChemPhysChem},
volume = {3},
number = {10},
pages = {871-879},
abstract = {Room temperature time-resolved luminescence measurements on single CdSe/ZnS quantum dots (QDs) are presented. Luminescence spectra were recorded over time periods of up to 30 min with a time resolution down to 6 ms. A clear 30 - 40 nm blue shift in the emission wavelength is observed for QDs in ambient air, before the luminescence stops after about 2 - 3 min due to photobleaching. The blue shift is absent in a nitrogen atmosphere and photo-bleaching occurs after much longer times, 10 - 15 min. These observations are explained by photoinduced oxidation. During illumination in the presence of oxygen the surface of CdSe is oxidized, which effectively results in shrinkage of the CdSe core diameter by almost 1 nm and, consequently, in a blue shift. This also influences the blinking behavior. The faster fading of the luminescence in air suggests that photoinduced oxidation results in the formation of nonradiative recombination centers at the CdSe/ CdSeOx interface. In a nitrogen atmosphere photoinduced oxidation is prevented by the absence of oxygen. A surprising observation is a higher initial light output for CdSe/ZnS QDs in air. We explain this higher light output by a fast reduction of the lifetime of the long-lived defect states of CdSe/ZnS QDs by oxygen.},
note = {cited By (since 1996) 107},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Blab200171,
title = {Two-photon excitation action cross-sections of the autofluorescent proteins},
author = {Gerhard A. Blab and Piet H.M. Lommerse and Laurent Cognet and Gregory S. Harms and Thomas Schmidt},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0012776120&partnerID=40&md5=ddfc6b34fa8c01492e90625686dfe0a9},
doi = {10.1016/S0009-2614(01)01282-9},
year  = {2001},
date = {2001-01-01},
journal = {Chemical Physics Letters},
volume = {350},
number = {1-2},
pages = {71-77},
note = {cited By 92},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Harms20012639,
title = {Single-molecule imaging of L-type Ca2+ channels in live cells},
author = {Gregory S. Harms and Laurent Cognet and Piet H.M. Lommerse and Gerhard A. Blab and Heike Kahn and Roland Gamsjäger and Herman P. Spaink and Nikolai M. Soldatov and Christoph Romanin and Thomas Schmidt},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0034759494&partnerID=40&md5=fca270cf07f3aa023b7209793ef796e9},
year  = {2001},
date = {2001-01-01},
journal = {Biophysical Journal},
volume = {81},
number = {5},
pages = {2639-2646},
note = {cited By 133},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Harms20012396,
title = {Autofluorescent proteins in single-molecule research: Applications to live cell imaging microscopy},
author = {Gregory S. Harms and Laurent Cognet and Piet H.M. Lommerse and Gerhard A. Blab and Thomas Schmidt},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0035033890&partnerID=40&md5=5655a2d31fd7439fb8a75238144f70e4},
year  = {2001},
date = {2001-01-01},
journal = {Biophysical Journal},
volume = {80},
number = {5},
pages = {2396-2408},
note = {cited By 169},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{Cognet20004052,
title = {Simultaneous dual-color and dual-polarization imaging of single molecules},
author = {Laurent Cognet and Gregory S. Harms and Gerhard A. Blab and Piet H.M. Lommerse and Thomas Schmidt},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0001759698&partnerID=40&md5=55e9630e8cbae934c79a89d9470a24a2},
year  = {2000},
date = {2000-01-01},
journal = {Applied Physics Letters},
volume = {77},
number = {24},
pages = {4052-4054},
note = {cited By 48},
keywords = {},
pubstate = {published},
tppubtype = {article}
}