Publications (34)9.55 Total impact
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Chapter: Oxygen Transport to Tissue XXXIII
01/2012: pages 263-268; -
Article: STED nanoscopy reveals molecular details of cholesterol- and cytoskeleton-modulated lipid interactions in living cells.
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ABSTRACT: Details about molecular membrane dynamics in living cells, such as lipid-protein interactions, are often hidden from the observer because of the limited spatial resolution of conventional far-field optical microscopy. The superior spatial resolution of stimulated emission depletion (STED) nanoscopy can provide new insights into this process. The application of fluorescence correlation spectroscopy (FCS) in focal spots continuously tuned down to 30 nm in diameter distinguishes between free and anomalous molecular diffusion due to, for example, transient binding of lipids to other membrane constituents, such as lipids and proteins. We compared STED-FCS data recorded on various fluorescent lipid analogs in the plasma membrane of living mammalian cells. Our results demonstrate details about the observed transient formation of molecular complexes. The diffusion characteristics of phosphoglycerolipids without hydroxyl-containing headgroups revealed weak interactions. The strongest interactions were observed with sphingolipid analogs, which showed cholesterol-assisted and cytoskeleton-dependent binding. The hydroxyl-containing headgroup of gangliosides, galactosylceramide, and phosphoinositol assisted binding, but in a much less cholesterol- and cytoskeleton-dependent manner. The observed anomalous diffusion indicates lipid-specific transient hydrogen bonding to other membrane molecules, such as proteins, and points to a distinct connectivity of the various lipids to other membrane constituents. This strong interaction is different from that responsible for forming cholesterol-dependent, liquid-ordered domains in model membranes.Biophysical Journal 10/2011; 101(7):1651-60. · 3.65 Impact Factor -
Article: Laser Doppler imaging for intraoperative human brain mapping.
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ABSTRACT: The identification and accurate location of centers of brain activity are vital both in neuro-surgery and brain research. This study aimed to provide a non-invasive, non-contact, accurate, rapid and user-friendly means of producing functional images intraoperatively. To this end a full field Laser Doppler imager was developed and integrated within the surgical microscope and perfusion images of the cortical surface were acquired during awake surgery whilst the patient performed a predetermined task. The regions of brain activity showed a clear signal (10-20% with respect to the baseline) related to the stimulation protocol which lead to intraoperative functional brain maps of strong statistical significance and which correlate well with the preoperative fMRI and intraoperative cortical electro-stimulation. These initial results achieved with a prototype device and wavelet based regressor analysis (the hemodynamic response function being derived from MRI applications) demonstrate the feasibility of LDI as an appropriate technique for intraoperative functional brain imaging.NeuroImage 12/2008; 44(4):1284-9. · 5.89 Impact Factor -
Conference Proceeding: Laser Doppler Imaging Opens New Perspectives for Intra-Operative Brain Mapping
Fortieth Annual Meeting of the Union of Swiss Societies for Experimental Biology (USGEB'08); 01/2008 -
Chapter: A look into life sciences - more than a side step from industrial inspection?
01/2003: pages 504-512; -
Article: Fabrication of arrays of sub-wavelength nano-apertures in an optically thick gold layer on glass slides for optical studies
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ABSTRACT: We report on the fabrication of two-dimensional arrays of nano-optical apertures in gold layers by electron beam lithography (EBL) on a transparent glass substrate. 30 x 30 μ m(2) large arrays of high aspect ratio sub-wavelength cylinders (400 nm diameter with period of 1.81 μ m) and annular apertures (diameters 250/330 nm and 3 10/330 nm inner/outer with period of 600 nm) were patterned in a 750 nm thick resist layer using a high contrast negative tone resist. The resist structures show sharp and vertical edges after development. The 150 nm thick deposited gold layer ensures optical transmission of less than 1.1 X 10(-4) at 633 nm wavelength. White light based optical characterizations agreed with theory predictions and prove the good quality of the structures. -
Article: Non equilibrium catalysis of single enzyme molecules
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Article: Confining the sampling volume for Fluorescence Correlation Spectroscopy using a sub-wavelength sized aperture
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ABSTRACT: For the observation of single molecule dynamics with fluorescence fluctuation spectroscopy (FFS) very low fluorophore concentrations are necessary. For in vitro measurements, this requirement is easy to fulfill. In biology however, micromolar concentrations are often encountered and may pose a real challenge to conventional FFS methods based on confocal instrumentation. We show a higher confinement of the sampling volume in the near- field of sub-wavelength sized apertures in a thin gold film. The gold apertures have been measured and characterized with fluorescence correlation spectroscopy (FCS), indicating light confinement beyond the far-field diffraction limit. We measured a reduction of the effective sampling volume by an order of magnitude compared to confocal instrumentation. (c) 2006 Optical Society of America. -
Article: Single Molecule Detection at Surfaces
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Article: Single molecule imaging of odorant receptors in supported planar lipid membranes
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Article: Single molecule imaging of odorant receptors in supported planar lipid membranes
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Article: Two color fluorescence correlation spectroscopy (FCS) and total internal reflection FCS
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Article: High-resolution Fourier domain optical coherence microscopy
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Article: Fourier Domain Optical Coherence Microscopy with extended depth of field
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Article: Highly confined depth focus for Fourier domain optical coherence microscopy
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Article: In vitro synthesis of GPCRs in a solid supported planar lipid membrane system
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Article: Dual-color Total Internal Reflection Fluorescence Fluctuation Spectroscopy
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ABSTRACT: We developed a dual-color total internal reflection fluorescence (TIRF) system for single molecule imaging and fluorescence fluctuation spectroscopy (FFS). For a performance analysis, we measured a synthetic binding assay with dual-color global fluorescence correlation spectroscopy (2CG-FCS) and dual-color fluorescence intensity distribution analysis (2D-FIDA). We show that dual-color TIR-FFS is a suitable method for measuring coincidence assays at the surface. In particular, our setup has a very high fluorescence collection efficiency resulting in a two- to three-fold increased molecular brightness. Using a customized workbench setup, we improved the setup alignment, the sample handling and the system versatility. -
Article: Single molecule imaging of odorant receptors in tethered lipid membranes
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Article: Single molecule detection at surfaces
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Article: Single molecule imaging of odorant receptors in supported planar lipid membranes
Top co-authors
Top Journals
- NeuroImage (1)
- Biophysical Journal (1)
Institutions
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2011
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Max-Planck-Institut für biophysikalische Chemie
- Department of NanoBiophotonics
Göttingen, Lower Saxony, Germany
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2008
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École Polytechnique Fédérale de Lausanne
- Laboratoire d'optique
Lausanne, VD, Switzerland -
Goethe-Universität Frankfurt am Main
- Institut für Neurochirurgie
Frankfurt am Main, Hesse, Germany
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