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At least 649 records · Page 36Linked to original sources
PubMed2005

Infrared laser light reduces loading time of dental implants: a Raman spectroscopic study.

OBJECTIVE: The aim of this study was to assess, through near-infrared Raman spectroscopy (NIRS), the incorporation of hydroxyapatite of calcium (CHA; approximately 960 cm(1))--on the healing bone around dental implants submitted or not to low-level laser therapy (LLLT) (lambda830 nm). BACKGROUND DATA: The process of maturation of the bone is important for the success of dental implants, as it improves the fixation of the implant to the bone, allowing the wearing of a prosthesis. LLLT has been suggested as a mean of improving bone healing because of its biomodulatory capabilities. METHODS: Fourteen rabbits received a titanium implant on the tibia; eight of them were irradiated with lambda830-nm laser (seven sessions at 48-h intervals, 21.5 J/cm(2) per session, 10 mW, phi approximately 0.0028 cm(2), 85 J/cm(2) treatment dose), and six acted as control. The animals were sacrificed at 15, 30, and 45 days after surgery. Specimens were routinely prepared for Raman spectroscopy. Twelve readings were taken on the bone around the implant. RESULTS: The results showed significant differences in the concentration of CHA on irradiated and control specimens at both 30 and 45 days after surgery (p < 0.001). CONCLUSION: It is concluded that LLLT does improve bone healing, and this can be safely assessed by Raman spectroscopy.

Animals↗
PubMed1999

Raman spectroscopy of protein and nucleic acid assemblies.

The Raman spectrum of a protein or nucleic acid consists of numerous discrete bands representing molecular normal modes of vibration and serves as a sensitive and selective fingerprint of three-dimensional structure, intermolecular interactions, and dynamics. Recent improvements in instrumentation, coupled with innovative approaches in experimental design, dramatically increase the power and scope of the method, particularly for investigations of large supramolecular assemblies. Applications are considered that involve the use of (a) time-resolved Raman spectroscopy to elucidate assembly pathways in icosahedral viruses, (b) polarized Raman microspectroscopy to determine detailed structural parameters in filamentous viruses, (c) ultraviolet-resonance Raman spectroscopy to probe selective DNA and protein residues in nucleoprotein complexes, and (d) difference Raman methods to understand mechanisms of protein/DNA recognition in gene regulatory and chromosomal complexes.

DNA↗
PubMed2000

[High temperature Raman spectroscopic study of the structure of sodium disilicate crystal, glass and its melt].

The structure of Na2Si2O5 from room temperature up to 1,773 K are studied by high temperature Raman spectroscopy using copper vapor pulse laser and integral time-resolved detection technique without any black-body radiation effect on spectral record. Back-scattering optical configuration is coupled with confocal collection of Raman signal of macro-sample in the high temperature shaft tube furnace. Results show that temperature-dependent Raman spectra can clearly indicate phase transition during melting. Relative densities of various kinds of SiO4(n-4) (n, bridging-oxygen number binding to one tetrahedron former Si) tetrahedrons can be qualitatively and quantitatively resolved by Gaussian spectral deconvolution. Obviously high temperature Raman spectroscopy provides an useful tool for the micro-structure research of materials under high temperature.

Crystallization↗
PubMed2006

[In situ resonance Raman spectra of organic pigments in freshwater cultured pearls].

In situ resonance Raman spectra of Chinese freshwater pearls were collected and analysed systematically with three different excitation wavelengths at lambda = 514, 633 and 785 nm. At the same time, the Raman spectra of eggshells of Pomacea canaliculata were also collected under the same experimental conditions in order to compare with pearls' Raman spectra. The conclusions were as follows: (1) Frequency dispersions of Raman spectra of organic pigments were obviously observed in Raman spectra of pearls. In contrast, Raman spectra of organic pigments in eggshells of Pomacea canaliculata showed no frequency dispersion phenomena; (2) It was considered that the organic pigments in pearls were polyacetylenic materials but not carotenoids which was proposed by previous researchers, and the organic pigments in eggshells of Pomacea canaliculata were carotenoids; (3) The conjugated (>=C number of polyacetylenic material in pearls was calculated to be about 10 and 16, and the conjugated C[double bond]C number of carotenoid in eggshells of Pomacea canaliculata was about 13 based on the Raman shifts caused by conjugated C[double bond]C double bonds.

Animals↗
PubMedDate not supplied

[Surface-enhanced Raman spectroscopy of biopolymers: membrane proteins, bacteriorhodopsin and rhodopsin adsorbed on silver electrodes and silver hydrosols].

Surface-enhanced Raman (SER) spectra of purple membranes of Halobacterium halobium and photoreceptor disks of the rod outer segments adsorbed on silver hydrosols were analysed. It has been shown that the intensity of SER spectra of bacterial and visual rhodopsins increases 5 X 10(4) times at adsorption. Concentration relationship of the signal intensity of SER spectra has the maximum at bacteriorhodopsin concentration about 2 X 10(-7) M. It has been shown that adsorption on silver hydrosol leads to fixation of light-induced photochemical transformations in bacterial and visual rhodopsins. Adsorption on the "smooth" electrodes at the potential of the zero charge of silver does not affect the photocycle of bacteriorhodopsin. An increase or decrease of the electrode potential relative to the zero charge point of silver leads to the accumulation of kinetic intermediate K610 and a decrease of the concentration of the form BRh570. It has been shown that on the "smooth" electrode primarily the long-range component of the SER mechanism is realized. Bands corresponding to the vibrations of the atom groups directly contacting with the metal are mainly intensified after redox cycle which increases the concentration of chemosorption centres. A conclusion is drawn that the method of SER spectroscopy of biomolecules adsorbed on "smooth" electrodes, permits obtaining information similar to that obtained from the analysis of Raman spectra of unadsorbed molecules, but at concentrations by two orders less. Adsorption on the electrodes treated with the help of redox cycle permits to obtain highly oriented preparations and to study topography of biopolymers in water solutions and suspensions.

Bacteriorhodopsins↗
PubMedDate not supplied

Raman spectroscopy in combination with background near-infrared autofluorescence enhances the in vivo assessment of malignant tissues.

The diagnostic ability of optical spectroscopy techniques, including near-infrared (NIR) Raman spectroscopy, NIR autofluorescence spectroscopy and the composite Raman and NIR autofluorescence spectroscopy, for in vivo detection of malignant tumors was evaluated in this study. A murine tumor model, in which BALB/c mice were implanted with Meth-A fibrosarcoma cells into the subcutaneous region of the lower back, was used for this purpose. A rapid-acquisition dispersive-type NIR Raman system was employed for tissue Raman and NIR autofluorescence spectroscopic measurements at 785-nm laser excitation. High-quality in vivo NIR Raman spectra associated with an autofluorescence background from mouse skin and tumor tissue were acquired in 5 s. Multivariate statistical techniques, including principal component analysis (PCA) and linear discriminant analysis (LDA), were used to develop diagnostic algorithms for differentiating tumors from normal tissue based on their spectral features. Spectral classification of tumor tissue was tested using a leave-one-out, cross-validation method, and the receiver operating characteristic (ROC) curves were used to further evaluate the performance of diagnostic algorithms derived. Thirty-two in vivo Raman, NIR fluorescence and composite Raman and NIR fluorescence spectra were analyzed (16 normal, 16 tumors). Classification results obtained from cross-validation of the LDA model based on the three spectral data sets showed diagnostic sensitivities of 81.3%, 93.8% and 93.8%; specificities of 100%, 87.5% and 100%; and overall diagnostic accuracies of 90.6%, 90.6% and 96.9% respectively, for tumor identification. ROC curves showed that the most effective diagnostic algorithms were from the composite Raman and NIR autofluorescence techniques.

Animals↗