Publications de Marcel Leutenegger

Chattez avec Graph Search

Posez n’importe quelle question sur les cours, conférences, exercices, recherches, actualités, etc. de l’EPFL ou essayez les exemples de questions ci-dessous.

AVERTISSEMENT : Le chatbot Graph n'est pas programmé pour fournir des réponses explicites ou catégoriques à vos questions. Il transforme plutôt vos questions en demandes API qui sont distribuées aux différents services informatiques officiellement administrés par l'EPFL. Son but est uniquement de collecter et de recommander des références pertinentes à des contenus que vous pouvez explorer pour vous aider à répondre à vos questions.

Monitoring biological relevant reactions on the single molecule level based on fluorescence spectroscopy techniques has become one of the most promising approaches for understanding a variety of phenomena in biophysics, biochemistry and life science. By ap ...

Membrane protein research depends largely on the availability of functional protein in an instrumental set- up for application of biophysical investigations. We used an in vitro synthesis strategy in the presence of a solid supported lipid membrane as a new experimental strategy for the expression and membrane insertion of complex membrane proteins. Thus we realized the insertion of such a complex membrane protein, the odorant receptor OR5 from rat, which belongs to the highly important class of G-Protein c

The measurement of tissue and cell oxygenation is important for understanding cell metabolism. We have addressed this problem with a novel optical technique, called triplet imaging, that exploits oxygen-induced triplet lifetime changes and is compatible with a variety of fluorophores. A modulated excitation of varying pulse widths allows the extraction of the lifetime of the essentially dark triplet state using a high-fluorescence signal intensity. This enables the monitoring of fast kinetics of oxygen conc

Odorant receptors are an excellent example of natural superiority in binding specific, small and hydrophobic molecules, and therefore are of particular interest in the development of a sensor platform for G protein-coupled receptors (GPCRs). Odorant receptors (OR5) of Rattus norvegicus were incorporated into model membranes by in vitro synthesis and vectorial incorporation for achieving natural receptor function. The vectorial insertion of OR5 into the planar membrane and their lateral distribution, their i

We present optical coherence correlation spectroscopy (OCCS), a novel method to study the motion dynamics of nanoparticles within many observation volumes simultaneously. For this purpose, OCCS combines the key features of dark-field optical coherence microscopy (dfOCM) and fluorescence correlation spectroscopy (FCS). dfOCM is a Fourier domain optical coherence microscopy technique offering micrometer three-dimensional spatial resolution and microseconds temporal sampling. The rapid temporal sampling is ach

We designed a fluorescence correlation spectroscopy (FCS) system for measurements on surfaces. The system consists of an objective-type total internal reflection fluorescence (TIRF) microscopy setup, adapted to measure FCS. Here, the fluorescence exciting ...

We present a rapid and flexible framework for the accurate calculation of the detection efficiency of fluorescence emission in isotropic media as well as in the vicinity of dielectric or metallic interfaces. The framework accounts for the dipole characteri ...

We present a new model of optical coherence tomography (OCT) taking into account multiple scattering. A theoretical analysis and experimental investigation reveals that in OCT, despite multiple scattering, the field backscattered from the sample is general ...

Optical microscopy has become a major non- or minimally invasive tool for investigating living organisms such as cells, tissues or small animals. Being such an essential tool for research and because lacking knowledge and insight in the working principles of tools often results in sub-optimal or outright wrong application, this books aims at teaching students in life sciences and biology the basic concepts for understanding their optical microscopes. In a first part, this manuscript starts by introducing ra

By switching fluorophores on and off in either a deterministic or a stochastic manner, superresolution microscopy has enabled the imaging of biological structures at resolutions well beyond the diffraction limit. Superresolution optical fluctuation imaging (SOFI) provides an elegant way of overcoming the diffraction limit in all three spatial dimensions by computing higher-order cumulants of image sequences of blinking fluorophores acquired with a conventional widefield microscope. So far, three-dimensional

We report results on two-photon total-internal-reflection fluorescence correlation spectroscopy with radially polarized light. The combination of liquid crystal spatial light modulator, providing radial polarization, with ultrafast laser (picosecond Nd:GdV ...

Odorant receptors are an excellent example of natural superiority in specifically binding specific, small and hydrophobic molecules. They are of particular interest in the development of a sensor platform for G protein- coupled receptors (GPCRs). Odorant receptors (OR5) of Rattus norvegicus were incorporated into model membranes by in vitro synthesis and vectorial incorporation for achieving natural receptor function. The vectorial insertion of OR5 into the planar membrane and their lateral distribution, th

Optical coherence correlation spectroscopy (OCCS) allows studying kinetic processes at the single particle level using the backscattered light of nanoparticles. We extend the possibilities of this technique by increasing its signal-to-noise ratio by a fact ...

We present the development and first application of a novel dual-color total internal reflection (TIR) fluorescence system for single-molecule coincidence analysis and fluorescence cross-correlation spectroscopy (FCCS). As a performance analysis, we measur ...

A classical technique to monitor dynamical processes at the single-molecule level is fluorescence correlation spectroscopy (FCS). However, FCS requires fluorescent labels that are typically limited by photobleaching and saturation. We present a new method, optical coherence correlation spectroscopy (OCCS), based on noble-metal nanoparticles that overcome those photobleaching and saturation limitations. OCCS is a correlation spectroscopy technique based on dark-field optical coherence microscopy (dfOCM), a F

We present a method for fast calculation of the electromagnetic field near the focus of an objective with a high numerical aperture (NA). Instead of direct integration, the vectorial Debye diffraction integral is evaluated with the fast Fourier transform for calculating the electromagnetic field in the entire focal region. We generalize this concept with the chirp z transform for obtaining a flexible sampling grid and an additional gain in computation speed. Under the conditions for the validity of the Deby

We report the design and application of a prism-based detection system for fluorescence (cross) correlation spectroscopy. The system utilizes a single laser wavelength for the simultaneous excitation of several dyes of different emission spectra. Fluoresce ...

A classical technique to monitor dynamical processes at the molecular level is fluorescence correlation spectroscopy (FCS). FCS requires fluorescent labels that are typically limited by photobleaching and saturation. We present a new method that uses noble-metal nanoparticles instead of fluorophores: optical coherence correlation spectroscopy (OCCS). OCCS is a correlation spectroscopy technique based on dark-field optical coherence microscopy, a Fourier domain optical coherence tomography technique. In OCCS

This contribution summarizes first some of our efforts in imaging G-protein-coupled receptor (GPCR) functional inserted into planar tethered lipid bilayer membranes (tBLMs) as a novel platform for biophysical studies. The authors introduced recently a nove ...

Marcel Leutenegger

Chattez avec Graph Search

Single molecule detection on surfaces

In vitro Synthesis of GPCRs in a Solid Supported Planar Lipid Membrane System

Triplet imaging of oxygen consumption during the contraction of a single smooth muscle cell (A7r5)

Imaging of G protein-coupled receptors in solid-supported planar membranes at the single molecule level

Optical Coherence Correlation Spectroscopy (OCCS)

Total internal reflection fluorescence correlation spectroscopy (TIR-FCS) with low background and high count-rate per molecule

Detection efficiency in total internal reflection fluorescence microscopy

Multiple scattering in optical coherence tomography. I. Investigation and modeling

Optical microscopy for biology and life sciences

Multiplane 3D superresolution optical fluctuation imaging

High volume confinement in two-photon total-internal- reflection fluorescence correlation spectroscopy

Imaging of G protein-coupled receptors in solid- supported planar membranes at the single molecule level

Visible light optical coherence correlation spectroscopy

Dual-color total internal reflection fluorescence cross- correlation spectroscopy

Optical Coherence Correlation Spectroscopy (OCCS)

Fast focus field calculations

Fast focus field calculations

Prism-based multicolor fluorescence correlation spectrometer

Optical Coherence Correlation Spectroscopy (OCCS)

Imaging of G protein-coupled receptors in solid-supported planar lipid membranes