A5081480013- Spectroscopy and Quantum Chemical Studies
- Photochemistry and Electron Transfer Studies
- Advanced Chemical Physics Studies
- Analytical Chemistry and Sensors
- Photoreceptor and optogenetics research
- Advanced Fluorescence Microscopy Techniques
- Porphyrin and Phthalocyanine Chemistry
- Molecular Spectroscopy and Structure
- Photosynthetic Processes and Mechanisms
- nanoparticles nucleation surface interactions
- Quantum, superfluid, helium dynamics
- Protein Structure and Dynamics
- Molecular Sensors and Ion Detection
- Spectroscopy and Laser Applications
- Nonlinear Optical Materials Studies
- Protein Interaction Studies and Fluorescence Analysis
- Luminescence and Fluorescent Materials
- Optical Imaging and Spectroscopy Techniques
- bioluminescence and chemiluminescence research
- Cyclopropane Reaction Mechanisms
- Electron Spin Resonance Studies
- Photoacoustic and Ultrasonic Imaging
- Synthesis and Reactivity of Heterocycles
- DNA and Nucleic Acid Chemistry
- Atomic and Subatomic Physics Research
University of Pennsylvania
2013-2023
California University of Pennsylvania
2018-2022
Philadelphia University
1993-2020
Laboratoire de physique des lasers
2015-2018
Optica
2013-2018
DuPont (United States)
2000-2007
Chinese Academy of Sciences
2007
Binghamton University
2004
Johns Hopkins University
2002
University of Bern
1989-1998
Fluorescence quenching in solutions of a pendant-functionalized conjugated polymer chemosensor (ttp-PPETE) has been evaluated the presence variety transition metal cations, including Ni2+, Co2+, Cu2+, Fe2+, and Cr6+. Photophysical analysis emission revealed static mechanism that demonstrated strong positive deviations from predicted linear behavior. The enhanced was found to correlate closely with relative loading cationic analytes on chemosensor. This behavior attributed rapid energy...
Imaging oxygen in 3D with submicron spatial resolution can be made possible by combining phosphorescence quenching technique multiphoton laser scanning microscopy. Because Pt and Pd porphyrin-based phosphorescent dyes, traditionally used as phosphors biological measurements, exhibit extremely low two-photon absorption (2PA) cross-sections, we designed a nanosensor for oxygen, which 2P absorbing antenna is coupled to metalloporphyrin core via intramolecular energy transfer (ET) the purpose of...
High-resolution images of oxygen distributions in microheterogeneous samples are obtained by two-photon laser scanning microscopy (2P LSM), using a newly developed dendritic nanoprobe with internally enhanced absorption (2PA) cross-section. In this probe, energy is harvested 2PA antenna, which passes excitation onto phosphorescent metalloporphyrin via intramolecular transfer. The 2P LSM allows sectioning gradients near diffraction-limited resolution, and lifetime-based acquisition eliminates...
Biodegradable polymer and nanorod (<1% by volume) composites are formulated that heat when exposed to infrared light undergo shape transitions (see image). The heating is repeatable tunable based on concentration intensity.
Neurophotonics was launched in 2014 coinciding with the launch of BRAIN Initiative focused on development technologies for advancement neuroscience. For last seven years, Neurophotonics' agenda has been well aligned this focus neurotechnologies featuring new optical methods and tools applicable to brain studies. While 2.0 is pivoting towards applications these novel quest understand brain, article we review an extensive diverse toolkit explore function that have emerged from related...
A water-soluble triacetic acid cryptophane-A derivative (TAAC) was synthesized and determined by isothermal titration calorimetry fluorescence quenching assay to have a xenon association constant of 33 000 M−1 at 293 K, which is the largest value measured for any host molecule date. Fluorescence lifetime measurements TAAC in presence varying amounts indicated static encapsulated second non-xenon-binding conformer solution. Acid−base titrations aqueous NMR spectroscopy previously...
Tryptophan (Trp) fluorescence has been widely used to interrogate the structure, dynamics, and function of proteins. In particular, it provides a convenient site-specific means probe protein's hydration status dynamics. Herein, we show that tryptophan analogue, 5-cyanotryptophan (TrpCN), can also be for this purpose, but with benefit enhanced sensitivity hydration. This conclusion is reached based on measurements static time-resolved properties 5-cyanoindole, TrpCN, TrpCN-containing peptides...
Van der Waals (vdW) clusters of naphthalene with argon were synthesized in supersonic beam expansions. Mass-selective absorption spectroscopy was carried out by using fragmentation-free two-color resonant two-photon ionization mass-spectrometric detection. Electronic spectra naph⋅Arn (n≤6) recorded at the vicinity S1←S0 electronic origin (32 020 cm−1 ), and corresponding for 8̄10 transition up to n=30. For n=3, due two different isomers could be separated. Clear evidence existence cluster...
Enhanced two-photon-absorbing (2PA) systems with triplet cores are currently under scrutiny for several biomedical applications, including photodynamic therapy (PDT) and two-photon microscopy of oxygen. The performance so far developed molecules, however, is substantially below expected. In this study we take a detailed look at the processes occurring in these propose ways to improve their performance. We focus on interchromophore distance tuning as means optimization sensors constructs,...
The demonstration of a nonlinear optical technique for directly monitoring adsorption surfactants on the surface microparticles in colloids is reported. In this approach, dye molecules with strong hyperpolarizability are first adsorbed particle to give detectable second-harmonic generation. surfactant then added colloidal solution competition surface. displacement results decrease signal, indicating molecules. A continuous flow/titration system combination high-repetition-rate femtosecond...
Metalloporphyrin-based phosphorescent nanoprobes are being developed for two-photon microscopy of oxygen. In these molecular constructs, the generation porphyrin triplet states following excitation is induced by intramolecular Förster-type resonance energy transfer from a covalently attached 2P antenna. earlier prototypes, electron between antenna and metalloporphyrin strongly interferred with phosphorescence, reducing sensitivity dynamic range sensors. By tuning distances core, adjusting...
The surface properties of carbon black microparticles in aqueous solution are characterized through adsorption a hydrophobic ion (malachite green) monitored by optical second-harmonic generation (SHG). Carbon particle surfaces with 14 different O/C ratios (from 0.028 to 0.270) have been examined. isotherm MG on the particles weighing as little 0.010 g can be measured using SHG during continuous titration molecule into solution. data allows determination free energy and reveals coherent...
The amino acids tryptophan and 4-cyanotryptophan constitute a dual FRET PET pair, useful for various biological applications.
The M2 proton channel of the influenza A virus has been subject extensive studies because its critical role in viral replication. As such, we now know a great deal about mechanism action, especially how it selects and conducts protons an asymmetric fashion. conductance this is tuned to conduct at relatively low biologically useful rate, which allows acidification interior entrapped within endosome, but not so as cause toxicity infected host cell prior packaging virus. dynamic, structural...
Abstract Achiral spiroactivated cyclopropanes are isomerized to optically active ( R )‐(cycloalk‐2‐enyl)‐ Meldrum 's acids = )‐5‐(cycloalk‐2‐enyl)‐2,2‐dimethyl‐1,3‐dioxane‐4,6‐diones) in high yield and ee's up 86% by catalytic amounts of cob(I)alamin polar protic solvents.
Cylcodextrin sugars are cyclic that have a hydrophilic exterior and hydrophobic center. This enables cyclodextrins to solubilize molecules in aqueous media. Cyclodextrins may inhibit aggregation by intercalating surface aromatic residues competing with interprotein clusters (pi-pi interactions). In order investigate this concept, the interaction of hydroxypropyl-beta-cyclodextrin (HPBCD) melittin is studied steady-state time-resolved fluorescence, fluorescence polarization, circular...
Oxygen concentration distributions in biological systems can be imaged by the phosphorescence quenching method combination with two-photon laser scanning microscopy. In this paper, we identified excitation regime which signal of a two-photon-enhanced phosphorescent probe (Finikova, O. S.; Lebedev, A. Y.; Aprelev, A.; Troxler, T.; Gao, F.; Garnacho, C.; Muro, Hochstrasser, R. M.; Vinogradov, S. ChemPhysChem 2008, 9, 1673−1679) is dependent quadratically on power (quadratic regime), and...
The fluorescence of <italic>p</italic>-cyanophenylalanine is quenched by selenomethionine through an electron transfer process occurring at short distances.
Considerable efforts have been devoted to the development of spectroscopic probes that are sensitive water and can be used monitor, for example, biological chemical processes involving dehydration or hydration. Continuing this line research, herein we show 7-cyanoindole serve as a fluorescence probe hydration its properties, including intensity, peak wavelength lifetime, depend on amount in nine water-organic solvent mixtures. Our results indicate is not only able reveal underlying...
Molecular dynamics simulations were performed for van der Waals clusters naphthalene⋅Arn, n=1 to 4. For all isomers and conformers of these clusters, dynamical quantities such as velocity autocorrelation functions, vibrational power spectra, semiclassical electronic absorption spectra calculated over a wide energy range, averaged canonical distribution at temperatures in the range T=5 30 K. Electronic origin bands according method [L. E. Fried S. Mukamel, J. Chem. Phys. 96, 116 (1992)] are...