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At least 541 records · Page 30Linked to original sources
PubMed2002

Laser trapping and Raman spectroscopy of single cellular organelles in the nanometer range.

The laser trapping technique combined with near-infrared Raman (NIR) spectroscopy was used for the analysis of single cellular organelles in the nanometer range. The samples were synaptosomes, nerve-ending particles (about 500-700 nm in diameter) isolated from a neuron in a rat brain, dispersed in the phosphate buffer solution. The NIR laser Raman trapping (NIR-LRT) system trapped a single synaptosome without photochemical damage and provided a Raman spectrum of the sample with less fluorescence background. After the background subtraction from the Raman spectrum, two large peaks appeared, which are attributed to the peaks of the CH(2) deformation mode and the amide I mode. This indicates the laser-trapped synaptosomes include some types of lipids and proteins. The result demonstrates that the NIR-LRT system can determine biological molecules in single cellular organelles in the nanometer range. Further improvement of the detection sensitivity will enable us to get detailed information about the functions of single cellular organelles in the brain, which will be valuable for neuroscience.

Lasers↗
PubMed2004

analysis of phthalate ester content in poly(vinyl chloride) plastics by means of fourier transform Raman spectroscopy.

Fourier transform (FT) Raman spectroscopy is applied to a range of phthalate ester plasticizers in pure form as well as in poly(vinyl chloride) (PVC) samples. It is found that phthalate esters as a group can be identified by a set of six characteristic Raman bands. FT-Raman spectra of 22 phthalate esters are given. It is demonstrated that the presence of phthalate esters in PVC products is readily detectable by FT-Raman spectroscopy. By use of proper reference samples quantitative determination of the phthalate ester content becomes possible as well.

Dibutyl Phthalate↗
PubMedDate not supplied

The use of optical spectroscopy in combinatorial chemistry.

Infrared and Raman spectroscopy allow direct spectral analysis of the solid-phase, thus avoiding the tedious cleavage of compounds from the solid support. With diagnostic bands in starting materials or products, infrared and Raman spectroscopy are efficient in monitoring each reaction step directly on the solid phase. Consequently, infrared and Raman spectroscopy have evolved as the premier analytical methodology for direct analysis on the solid support. While infrared transmission spectroscopy is a general analytical method for resin samples, internal reflection spectroscopy is especially suited for solid polymer substrates known as "pins" or "crowns." Single bead analysis is done best by infrared microspectroscopy, whereas photoacoustic spectroscopy allows totally nondestructive analysis of resin samples. With an automated accessory, diffuse reflection spectroscopy provides a method for high throughput on-bead monitoring of solid-phase reactions. Providing identification based on molecular structure, HPLC-FTIR is, therefore, complementary to LC-MS. Additionally, Raman spectroscopy as a complement to infrared spectroscopy can be applied to resin samples and-using a Raman microscope-to single beads. Fluorometry as an extremely sensitive spectroscopic detection method allows rapid quantification of organic reactions directly on the resin.

Chromatography, Liquid↗
PubMed2000

Effect of water on the formamide-intercalation of kaolinite.

The molecular structures of low defect kaolinite completely intercalated with formamide and formamide-water mixtures have been determined using a combination of X-ray diffraction, thermoanalytical techniques, DRIFT and Raman spectroscopy. Expansion of the kaolinite to 10.09 A was observed with subtle differences whether the kaolinite was expanded with formamide or formamide-water mixtures. Thermal analysis showed that greater amounts of formamide could be intercalated into the kaolinite in the presence of water. New infrared bands were observed for the formamide intercalated kaolinites at 3648, 3630 and 3606 cm(-1). These bands are attributed to the hydroxyl stretching frequencies of the inner surface hydroxyls hydrogen bonded to formamide with water, formamide and interlamellar water. Bands were observed at similar positions in the Raman spectrum. At liquid nitrogen temperature, the 3630 cm(-1) Raman band separated into two bands at 3633 and 3625 cm(-1). DRIFT spectra showed the hydroxyl deformation mode at 905 cm(-1). Changes in the molecular structure of the formamide are observed through both the NH stretching vibrations and the amide 1 and 2 bands. Upon intercalation of kaolinite with formamide, bands are observed at 3460, 3344, 3248 and 3167 cm(-1) attributed to the NH stretching vibration of the NH involved with hydrogen bonded to the oxygens of the kaolinite siloxane surface. In the DRIFT spectra of the formamide intercalated kaolinites bands are observed at 1700 and 1671 cm(-1) and are attributed to the amide 1 and amide 2 vibrations.

Amides↗
PubMed1979

Laser Raman spectroscopy of acid phosphatase from rat liver after neuraminidase treatment.

The conventional Raman technique was used to obtain spectra of acid phosphatase isoenzymes I and II from rat liver after neuraminidase enzyme treatment for 24 h. The low frequency bands below 300 cm-1 which were observed in native lyophilized isoenzymes are obtained from the sialic acid groups of these glycoproteins. These bands disappeared after neuraminidase treatment and the broad bands at 310, 260, 200 and 80 cm-1 are obtained from protein modes. The small differences between the Raman spectra of these isoenzymes disappeared after the neuraminidase treatment.

Acid Phosphatase↗
PubMed2001

In-situ spectroscopic investigations of the redox behavior of poly(indole-5-carboxylic-acid) modified electrodes in acidic aqueous solutions.

The oxidation of electrochemically grown poly(indole-5-carboxylic-acid) (P5CO2H) and its spectroscopic properties have been studied by in-situ spectroelectrochemical techniques. The purpose of this paper is to characterize the different modifications on the P5CO2H backbone, induced by the electrochemical oxidation in aqueous acidic solution. We have identified, on the basis of Raman spectra, the vibrational modes associated with neutral and oxidized segments of polymer. It was shown that at least three chemically and optically different species (perhaps other products too) are produced in different potential regimes upon oxidation of this polymer. The results obtained also indicate that the molecular properties of this conducting polymer are better revealed by in-situ resonant spectra than by ex-situ infrared and Raman studies.

Carboxylic Acids↗
PubMed1995

Raman spectroscopy of normal and diseased human breast tissues.

Raman spectra of histologically normal human breast biopsy samples were compared to those exhibiting infiltrating ductal carcinoma (IDC) or fibrocystic change. Experiments at 784 nm with CCD detectors reduced fluorescence interference and produced high SNR spectra with relatively low (10-200 mW) laser power. Sample to sample and patient to patient variation for normal specimens were less than 5% for the ratios of major Raman bands. The Raman spectra changed dramatically in diseased specimens, with much weaker lipid bands being evident. The spectrum of infiltrating ductal carcinoma samples is similar to that of human collagen. Differences between benign (fibrocystic) and malignant (IDC) lesions were smaller than those between normal and IDC specimens, but were still reproducible. Fiberoptic sampling through a hypodermic needle and with a remote probe were demonstrated. The possibility of rapid diagnosis with Raman spectroscopy is considered.

Biopsy↗
PubMed2000

Intensities of E. coli nucleic acid Raman spectra excited selectively from whole cells with 251-nm light.

Escherichia coli bacteria in the logarithmic growth phase have been investigated by UV resonance Raman spectroscopy. Bacterial whole-cell Raman spectra excited at 251 nm reflect nearly exclusively the nucleic acid composition even though a very large fraction of the bacterial mass is composed of protein. It has been demonstrated that if bacteria are grown under controlled (logarithmic growth) conditions, which give rise to organisms of known average biochemical composition, the intensities of E. coli Raman spectra can be explained quantitatively from the knowledge of component nucleic acid base resonance Raman cross sections.

DNA, Bacterial↗