IR AND RAMAN-SPECTRA STUDIES OF THE RARE EARCH COMPLEXES WITH GLUTATHIONE

The complexes of rare earth ions with glutathione were prepared and charactrized by IR and Raman spectroscopy in the solid state. Based on the spectral results, the structure and coordination sites of the ligand in these complexes were determined.

Diagnosis of colorectal cancer using Raman spectroscopy of laser-trapped single living epithelial cells

A single-cell diagnostic technique for epithelial cancers is developed by utilizing laser trapping and Raman spectroscopy to differentiate cancerous and normal epithelial cells. Single-cell suspensions were prepared from surgically removed human colorectal tissues following standard primary culture protocols and examined in a near-infrared laser-trapping Raman spectroscopy system, where living epithelial cells were investigated one by one. A diagnostic model was built on the spectral data obtained from 8 patients and validated by the data from 2 new patients. Our technique has potential applications from epithelial cancer diagnosis to the study of cell dynamics of carcinogenesis. (c) 2006 Optical Society of America.

SYNTHESIS AND VIBRATIONAL SPECTRUM STUDIES OF RARE EARTH COMPLEXES WITH CYCLOHEXANE CARBOXYLIC ACID

The solid state complexes of trivalent lanthanid, yttrium and scandium with cyclohexane carboxylic acid have been isolated and characterized by IR and Raman spectroscopy. It was found that there are only chelated carboxylate groups in the scandium complex and that there are the chelated, bridged and chelate-bridged carboxylate groups in other rare earth complexes. The former is a mononuclear complex and the latter is a polynuclear polymer. The RE—O coordinate bonds possess the characters of convalent ionic ...

Raman spectroscopy and luminescent properties of ZnO nanostructures fabricated by femtosecond laser pulses

In this paper, we report the laser-induced periodic structure with different spatial characteristics on the surface of polished ZnO single-crystalline by high repetition rate femtosecond laser pulses. This study demonstrates that, using different laser parameters and irradiation conditions, ZnO nanoripples and nanorods were successfully prepared. We have investigated the surface by means of scanning electron microscope (SEM), Raman scattering and photoluminescence (PL). We propose that second-order harmonic has a strong influence on the formation of nanostructures. (c) 2007 Elsevier B.V All rights reserved.

Nonradiative recombination centers in Ga(As,N) and their annealing behavior studied by Raman spectroscopy

Nitrogen-related defects in diluted Ga(As,N) have been detected by Raman scattering in resonance with the localized E+ transition. These defects are attributed to local vibrational modes of nitrogen dimers on Ga- and As-lattice sites. Rapid thermal annealing under appropriate conditions is found to be able to remove the nitrogen dimers. The required minimum annealing temperature coincides with the threshold-like onset of strong, near-band-gap photoluminescence. This finding suggests that the nitrogen dimers are connected with nonradiative recombination centers. (C) 2004 American Institute of Physics.

Characterization of stress induced in SOS and Si/gamma-Al2O3/Si heteroepitaxial thin films by Raman spectroscopy

Raman spectroscopy technique has been performed to investigate the stress induced in as-grown silicon-on-sapphire (SOS), solid-phase-epitaxy (SPE) re-grown SOS, and Si/gamma-Al2O3/Si double-heteroepitaxial thin films. It was demonstrated that the residual stress in SOS film, arising from mismatch and difference of thermal expansion coefficient between silicon and sapphire, was reduced efficiently by SPE process, and that the stress in Si/gamma-Al2O3/Si thin film is much smaller than that of as-grown SOS and SPE upgraded SOS films. The stress decrease for double heteroepitaxial film Si/gamma-Al2O3/Si mainly arises from the smaller lattice mismatching of 2.4% between silicon top layer and the gamma-Al2O3/Si epitaxiial composite substrate, comparing with the large lattice mismatch of 13% for SOS films. It indicated that gamma-Al2O3/Si as a silicon-based epitaxial substrate benefits for reducing the residual stress for further growth of silicon layer, compared with on bulk sapphire substrate. (c) 2005 Elsevier B.V. All rights reserved.

Raman spectroscopy of apatite irradiated with swift heavy ions with and without simultaneous exertion of high pressure

Durango apatite was irradiated with energetic U ions of 2.64 GeV and Kr ions of 2.1 GeV, with and without simultaneous exposure to a pressure of 10.5 GPa. Analysis by confocal Raman spectroscopy gives evidence of vibrational changes being marginal for fluences below 5x10(11) ions/cm(2) but becoming dominant when increasing the fluence to 8x10(12) ions/cm(2). Samples irradiated with U ions experience severe strain resulting in crystal cracking and finally breakage at high fluences. These radiation effects are directly linked to the formation of amorphous tracks and the fraction of amorphized material increasing with fluence. Raman spectroscopy of pressurized irradiated samples shows small shifts of the band positions with decreasing pressure but without a significant change of the Gruneisen parameter. Compared to irradiations at ambient conditions, the Raman spectra of apatite irradiated at 10.5 GPa exhibit fewer modifications, suggesting a higher radiation stability of the lattice by the pressure applied.

Large-scale, rapid synthesis and application in surface-enhanced Raman spectroscopy of sub-micrometer polyhedral gold nanocrystals

Macromolecule-protected sub-micrometer polyhedral gold nanocrystals have been facilely prepared by heating an aqueous solution containing poly (N-vinyl-2-pyrrolidone) (PVP) and HAuCl4 without adding other reducing agents. Scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), ultraviolet-visible-near-infrared spectroscopy (UV-vis-NIR), and x-ray diffraction (XRD) were employed to characterize the obtained polyhedral gold nanocrystals. It is found that the 10:1 molar ratio of PVP to gold is a key factor for obtaining quasi-monodisperse polyhedral gold nanocrystals. Furthermore, the application of polyhedral gold nanocrystals in surface-enhanced Raman scattering (SERS) was investigated by using 4-aminothiophenol (4-ATP) as a probe molecule. The results indicated that the sub-micrometer polyhedral gold nanocrystals modified on the ITO substrate exhibited higher SERS activity compared to the traditional gold nanoparticle modified film. The enhancement factor (EF) on polyhedral gold nanocrystals was about six times larger than that obtained on aggregated gold nanoparticles (similar to 25 nm).

Wet-chemical approach to three-dimensional gold nanocorallines: Synthesis and application in surface-enhanced Raman spectroscopy

The shape-con trolled synthesis of micrometer- sized gold nanocoralline was simply realized via a wet-chemical approach. The as-prepared hierarchical gold nanocorallines (HGNs) on the solid substrate were initially applied in SERS analysis with 4-aminothiophenol (4-ATP) as the probe molecule. The HGN-modified glass substrate exhibits a higher SERS effect (one order of magnitude higher) than the aggregated gold nanoparticle (similar to 25 nm)-modified glass substrate.

Surface-enhanced resonance Raman spectroscopy and spectroscopy study of redox-induced conformational equilibrium of cytochrome c adsorbed on DNA-modified metal electrode

The redox-induced conformational equilibrium of cytochrome c (cyt c) adsorbed on DNA-modified metal electrode and the interaction mechanism of DNA with cyt c have been studied by electrochemical, spectroscopic and spectroelectrochemical techniques. The results indicate that the external electric field induces potential-dependent coordination equilibrium of the adsorbed cyt c between its oxidized state (with native six-coordinate low-spin and non-native five-coordinate high-spin heme configuration) and its reduced state (with native six-coordinate low-spin heme configuration) on DNA-modified metal electrode. The strong interactions between DNA and cyt c induce the self-aggregation of cyt c adsorbed on DNA. The orientational distribution of cyt c adsorbed on DNA-modified metal electrode is potential-dependent, which results in the deviation from an ideal Nernstian behavior of the adsorbed cyt c at high electrode potentials. The electric-field-induced increase in the activation barrier of proton-transfer steps attributed to the rearrangement of the hydrogen bond network and the self-aggregation of cyt c upon adsorption on DNA-modified electrode strongly decrease the interfacial electron transfer rate.

Study of FT-Raman Spectroscopy on the Effects of Lanthanide Ions and Their Complexes on the Fluidity of Dipalmitoylphosphatidylethanolamine Bilayer

The effects of lanthanide ions and their complexes of citrate and DTPA ligands on the fluidity of dipalmitoylphosphatidylethanolamine (DPPE) bilayers have been studied by FT-Raman spectroscopy. the results show that lanthanide ions of lower concentrationn decrease the fluidity of acyl chains of DPPE bilayers and change the conformation of C C-C backbone from gauche to the trans lanthanide ions of higher concentration, however, increase the fluidity of acyl chains and increase the gauche population of C-C-C backbone. Lanthanide complex of citrate have no effect on the fluidity of acyl chains of DPPE bilayers in the region of experimental concentration, but La-DTPA complex increase slightly the fluidity of acyl chains. the results also indicated that lanthanide ion of lower concentration changed the lattice packing of hydrocarbon chains from hexagonal form to orthorhombic form, but it is still in hexagonal or distorted hexagonal lattice cell in the gel state in the presence of metal ions and lanthanide complexes of higher concentration

Sensitivity map of laser tweezers Raman spectroscopy for single-cell analysis of colorectal cancer

Raman spectroscopy on single, living epithelial cells captured in a laser trap is shown to have diagnostic power over colorectal cancer. This new single-cell technology comprises three major components: primary culture processing of human tissue samples to produce single-cell suspensions, Raman detection on singly trapped cells, and diagnoses of the cells by artificial neural network classifications. it is compared with DNA flow cytometry for similarities and differences. Its advantages over tissue Raman spectroscopy are also discussed. In the actual construction of a diagnostic model for colorectal cancer, real patient data were taken to generate a training set of 320 Raman spectra and, a test set of 80. By incorporating outlier corrections to a conventional binary neural classifier, our network accomplished significantly better predictions than logistic regressions, with sensitivity improved from 77.5% to 86.3% and specificity improved from 81.3% to 86.3% for the training set and moderate improvements for the test set. Most important, the network approach enables a sensitivity map analysis to quantitate the relevance of each Raman band to the normal-to-cancer transform at the cell level. Our technique has direct clinic applications for diagnosing cancers and basic science potential in the study of cell dynamics of carcinogenesis. (C) 2007 Society of Photo-Optical Instrumentation Engineers.