@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}

}

@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{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 = {},

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 = {},

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 = {},

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}

}

@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{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 = {},

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{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{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{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}

}

@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}

}

@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{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{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{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}

}