A5044728864- Advanced Fluorescence Microscopy Techniques
- Photochemistry and Electron Transfer Studies
- Spectroscopy and Quantum Chemical Studies
- Molecular Junctions and Nanostructures
- Analytical Chemistry and Sensors
- Advanced biosensing and bioanalysis techniques
- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Near-Field Optical Microscopy
- Protein Structure and Dynamics
- Photonic and Optical Devices
- DNA and Nucleic Acid Chemistry
- Photosynthetic Processes and Mechanisms
- Advanced Electron Microscopy Techniques and Applications
- Lanthanide and Transition Metal Complexes
- Quantum Dots Synthesis And Properties
- Photoreceptor and optogenetics research
- Metal-Catalyzed Oxygenation Mechanisms
- Advanced Biosensing Techniques and Applications
- RNA Interference and Gene Delivery
- Crystallography and molecular interactions
- Porphyrin and Phthalocyanine Chemistry
- Magnetism in coordination complexes
- Lipid Membrane Structure and Behavior
- Enzyme Structure and Function
University of Lübeck
2012-2023
University of Duisburg-Essen
2017-2023
Washington Center
2016
University of Washington
2016
University of Bayreuth
2013
Johannes Gutenberg University Mainz
2003-2010
Martin Luther University Halle-Wittenberg
2004-2007
Luther University
2007
Max Planck Institute for Polymer Research
2004
ETH Zurich
2001-2002
Single-molecule Förster resonance energy transfer (smFRET) is increasingly being used to determine distances, structures, and dynamics of biomolecules in vitro vivo. However, generalized protocols FRET standards ensure the reproducibility accuracy measurements efficiencies are currently lacking. Here we report results a comparative blind study which 20 labs determined (E) several dye-labeled DNA duplexes. Using unified, straightforward method, obtained with s.d. between ±0.02 ±0.05. We...
Abstract Single-molecule Förster-resonance energy transfer (smFRET) experiments allow the study of biomolecular structure and dynamics in vitro vivo. We performed an international blind involving 19 laboratories to assess uncertainty FRET for proteins with respect measured efficiency histograms, determination distances, detection quantification structural dynamics. Using two protein systems distinct conformational changes dynamics, we obtained ≤0.06, corresponding interdye distance precision...
Perylenemonoimide chromophores, attached to a small dendron arm embedded in the polymer hosts Zeonex, poly(vinylbutyral), and poly(methyl methacrylate), are studied by means of laser-induced confocal fluorescence detection. Transient intensity exhibits dark periods on two different time scales: 100 μs scale considerably longer scale, ranging from ms as much tens seconds under high-vacuum conditions. The exponentially distributed short "off" times attributed triplet excursions molecule....
The influence of oxygen on the photophysical properties individual DiI18 molecules has been investigated by means both wide field and confocal scanning optical fluorescence microscopy. Excited close to saturation intensity, single-molecule detected in a charge-coupled device camera showed dramatic increase at exposure air compared when sample was protected from nitrogen flush. change triplet lifetime dye due quenching measured real time resolved single photon counting. In presence oxygen,...
We have investigated electronic excitation transfer in individual molecular dimers by time and spectrally resolved confocal fluorescence microscopy. The single molecule measurements allow for directly probing the distribution of coupling strengths due to static disorder polymer host. find where is delocalized (superradiant emission) while others emission originates from a localized state. Transitions between states as observed given dimer are attributed structural fluctuations guest-host system.
The fluorescence of individual pairs perylenemonoimide chromophores coupled via a short rigid linker is investigated. Photon antibunching reported, indicating collective effects in the fluorescence, which are further substantiated by observation triplet off times and lifetime shortening. experimental findings analyzed terms singlet-singlet singlet-triplet annihilation based on Förster type energy transfer. results reported here demonstrate that statistical properties emission light isolated...
Something to fret about: Luminescent semiconductor nanocrystals are covered with polymeric ligands which form many bonds the nanocrystal (NC) and increase their solubility. The decorated an organic dye molecule (see picture) so that electronic interaction in individual nanocrystal–dye complexes can be investigated by fluorescence resonance energy transfer (FRET) experiments. results show factors influence FRET results.
We investigate photoblinking and photobleaching of perylene diimide (PDI) its higher homologue terrylene (TDI). Single molecule fluorescence trajectories the dye molecules embedded in PMMA under ambient conditions exhibit "on"-"off" blinking time range from ms to s. Due limited statistics individual we construct ensemble distributions "on" "off" times which follow power laws with similar law coefficients (m(on) ≈ 1.18, m(off) 1.31). The is attributed reversible formation radical cations are...
A method to identify single molecules rapidly and with high efficiency based on simple probability considerations is proposed. In principle, any property of a detected photon in single-molecule fluorescence experiment, e.g., emission wavelength, arrival time after pulsed excitation, polarization, can be analyzed within the framework outlined methodology. Monte Carlo simulations show that less than 500 photons are needed assign an observed molecule one out four species confidence level higher...
Functionalized nanoporous alumina is applied in single-molecule fluorescence detection nanoscale confinement (see schematic image). The leads to apparent 1D diffusion with up 19-fold prolonged times through the focus. Single-molecule porous a promising tool for study of dynamical processes macromolecular systems and highly parallel ultrasensitive analytical applications.
One of the unique features single molecule absorption and emission is their anisotropy due to well-defined transition dipole(s) for both processes allowing determination molecule’s orientation. While polarization-resolved techniques are usually capable detecting only a projection dipole, several methods have been proposed in order determine full three-dimensional Here, we report on detection scheme that allows shot-noise limited dipole orientation utilizing an annular mirror, polarizing beam...
The power of three-dimensional orientation detection single emitting dipoles using a sophisticated scheme with three detectors in confocal microscope is quantitatively explored by means Monte Carlo simulations. We show that several hundreds photons are sufficient for reliable determination. In typical single-molecule experiments, time resolutions the submillisecond range trajectories become accessible. Experimental data on fluorescent latex beads and perylene monoimide molecules properly...
Abstract Spectral diffusion as a result of both the transitions between different molecular conformers and ′′molecular softness′′ quasi‐free perylene diimides on SiO 2 surface is investigated by means single‐molecule spectroscopy, which reveals time dependence fluorescence spectra three‐dimensional orientation. wavelengths all single emitters cover wide energy range about 0.27 eV, due to types with large differences in optical transition energy. Time‐dependent spectral trajectories within...
To prepare modified silica nanospheres for emulsion polymerization, a new agglomeration-free change of dispersion media has been developed. Nanosized spheres were synthesized by the Stöber method and directly with silane coupling agent. these particles subsequent medium was changed in two-step process from ethanol to water without agglomeration particles. The polymerization leads hemispherical single-core-structured silica–polystyrene composite thickness polymer shell can be altered varying...
Long chain running: The polymerization performance of guanidinato titanium(IV) olefin catalysts is tuned by monodentate ancillary ligands. Polymerization activities up to 8800 kgPE molcat.−1 h−1 bar−1 together with molecular weights 2500 kg mol−1 were observed (see figure; d-MAO=dry methylalumoxane). Ligand transfer the additional donor ligands has be avoided.
We report on the determination of three-dimensional orientation donor and acceptor transition dipoles in individual fluorescence resonance energy transfer (FRET) pairs by means scanning optical microscopy with annular illumination. Knowledge mutual dipole is mandatory for reliable distance based FRET efficiency measurements. In our model system perylenediimide as terryelenediimide are coupled via a stiff p-terphenyl linker. The absorption selectively addressed 488 nm 647 line an Ar/Kr mixed...
We report on fluorescence fluctuations of nanoparticles diffusing through a laser focus. Subject to an intensity threshold the signal is transformed into time traces and off periods. The distribution functions experimental times follow power laws t -alpha over several orders magnitude with exponents alpha approximately 1.5-2. At long cross exponential decays. For interpretation data diffusion-reaction equation proposed which covers both, diffusion controlled recurrence photon statistics as...
We report on the simultaneous detection of fluorescence lifetime, spectrum, and three-dimensional dipole orientation determination single perylene diimide molecules deposited a silica surface as model system for studying fluorophore internal orientational dynamics. employ multi-parameter scheme to demonstrate how jumps in molecule can be disentangled from spectral jumps, both leading changes detected total intensity. The lifetime determined simultaneously same photons is also sensitive with...
We developed a cryostat suitable for laser scanning confocal microscope which allows short working distance and thus the usage of an objective with high numerical aperture ensuring collection efficiency. The in situ preparation thin layer amorphous water is realized part cryostat, Dewar vessel, put onto custom-made, liquid-nitrogen immersed spin-coater. First tests on setup are performed perylenemonoimide/polymethyl methacrylate model system using standard oil dry at ambient temperature as...
Abstract Single-molecule FRET (smFRET) has become an established tool to study biomolecular structure and dynamics in vitro live cells. We performed a worldwide blind involving 19 labs assess the uncertainty of experiments for proteins with respect measured efficiency histograms, determination distances, detection quantification structural dynamics. Using two protein systems that undergo distinct conformational changes, we obtained less than ± 0.06, corresponding interdye distance precision...
Freeze-casting consists of freezing a liquid suspension (aqueous or other), followed by sublimation the solidified state to gas under reduced pressure, and subsequent sintering remaining scaffold consolidate densify struts walls. The structure is very porous with pores being replica solvent crystals. technique rather versatile use (water most time) as pore forming agent strong asset. has also been developed near net shape route yielding dense ceramics. In this work we report on composite...