Localization Study of Co-Phthalocyanines in Cells by Raman Micro(spectro)scopy

An investigation of intracellular localization of Co-phthalocyanines is reported. The Raman images of K562 cells stained with phthalocyanine were acquired. To understand the peculiarities of the Raman images, measurements were performed at different z-axis positions. The intracellular concentration of phthalocyanine was estimated. A colocalization study was carried out using the fluorescence probes FITC-dextran and acridine orange by means of Raman and fluorescence microscopy. Partial colocalization with both probes was revealed

Polarization-Sensitive CARS of the Amide I Band of Pure and Liganded Chymotrypsin

Polarization-sensitive coherent anti-Stokes Raman scattering (PSCARS) is used to investigate the secondary structure of the protein chymotrypsin, both free and bound to antranilic acid. Advantage is taken of the extreme sensitivity of the PSCARS spectra to the orientation of the analyser. Clear changes are observed in the protein spectra as a result of binding to antranilic acid. It is concluded that PSCARS can be fruitfully applied to detect changes in the bonds of the peptide backbone of enzymatic proteins as a result of substrate binding

An accretive mechanism for blue-shifted fluorescence in strongly pumped systems:resonance energy transfer with Raman emission

Since Kaiser and Garrett's pioneering work on two-photon absorption 40 years ago, observations of blue-shifted fluorescence have been widely used as a marker and measure of non-linear excitation. In doped crystals or in molecular multi-chromophore systems, where resonance energy transfer conveys excitation from the sites of initial photoabsorption to others which yield the fluorescence, this process can play a possible intermediary role in the generation of two-photon fluorescence. Recent work has revealed other competing mechanisms, involving energy transfer between three fluorophore sites, that should be equally or more significant in strongly pumped systems depending on the conditions. It is the purpose of this paper to identify fully the characteristics of one such process involving the coupling of fluorescence energy transfer with Raman emission, and to determine the precise nature of the conditions under which it may be observed

Polarization sensitive coherent anti-Stokes Raman scattering spectroscopy of the amide I band of proteins in solutions

Polarization sensitive coherent anti-Stokes Raman scattering (PCARS) spectroscopy is a fruitful technique to study Raman vibrations of diluted molecules under off-electron resonant conditions. We apply PCARS as a direct spectroscopic method to investigate the broad amide I band of proteins in heavy water. In spontaneous Raman spectroscopy, this band is not well resolved. We fit a number of spectra taken of each protein under different polarization conditions, with a single set of parameters. It then appears that some substructure is observed in the amide I band. From this substructure, we determine the percentage of alpha-helix, beta-sheet, and random coil for the proteins lysozyme, albumin, ribonuclease A, and alpha-chymotrypsin