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Optical-trapping confocal Raman microscopy is developed as a method to study the interactions of drugs or other compounds with the membranes of individual phospholipid vesicles. This technique allows membrane disorder, permeability, and drug localization to be assessed without the need for labeling of the membrane or the compounds of interest. We have applied this technique to study the interactions of two nonsteroidal antiinflammatory drugs, salicylate and ibuprofen, with vesicles prepared from 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). The results show that both salicylate and ibuprofen increase membrane disorder, as determined from increases in the Raman scattering from gauche conformers in the phospholipid acyl chains. By monitoring the Raman scattering of the drug molecules in optically trapped DMPC vesicles, the membrane permeability and partitioning of the drugs could be determined; the spatial distributions of the drugs were also measured by scanning the laser focus through surface-adhered 1,2-dipalmitoyl-sn -glycero-3-phosphocholine vesicles, producing a profile of the vesicle and its contents. Though the membrane is permeable to both drugs, ibuprofen preferentially accumulates in the membrane, whereas salicylate does not. The measured ibuprofen accumulation agrees quantitatively with the water/octanol partition coefficient of the drug and the estimated volume of the lipid membrane. The results suggest that ibuprofen localizes in the hydrophobic acyl chain region of the membrane, whereas salicylate weakly associates with the phospholipid headgroups. [ABSTRACT FROM AUTHOR]

Various silica-based microreactors have been designed that use enzyme immobilization to address technical concerns in proteolysis including inefficient and incomplete protein digesfon. Most of current designs for proteolytic reactors can improve either protease stability or proteolysis efficiency of individual protein(s). However, the desired features such as rapid digestion, larger sequence coverage, and high sensitivity have not been achieved by a single microreactor design for broad range proteins with diverse physical properties. Here, unlike conventional enzyme immobilization strategies, we describe a novel proteolytic nanoreactor based on the unique three-dimensional nanopore structure of our newly synthesized mesoporous silica (MPS), FDU-12, which integrates substrate enrichment, ‘reagent-free’ protein denaturation, and efficient proteolytic digestion. In our design, protein substrates were first captured by MPS nanopore structure and were concentrated from the solution. Following the pH change and applying trypsin, the denaturation and concurrent proteolysis of broad-range proteins were efficiently achieved. In minutes, many more sample peptides from the in-nanopore digestion of protein mixtures were detected by mass spectrometry, resulting in the identifications of a broad range of diverse proteins with high sequence coverage. The unique features of FDU-12 nanostructure that allow rapid, complete proteolysis and resulting enhanced sequence coverage of individual proteins were investigated by using Raman spectroscopy and comparative studies with respect to other MPSs. [ABSTRACT FROM AUTHOR]

A new nanoparticle-based chemiluminescent (CL) method has been developed for the ultrasensitive detection of DNA hybridization. The assay relies on a sandwich-type DNA hybridization in which the DNA targets are first hybridized to the captured oligonucleotide probes immobilized on polystyrene microwells and then the silver nanoparticles modified with alkylthiol-capped oligonucleolides are used as probes to monitor the presence of the specific target DNA. After being anchored on the hybrids, silver nanoparticles are dissolved to Ag+ in HNO3 solution and sensitively determined by a coupling CL reaction system (Ag+-Mn2+-K2S2O8-H3PO4-luminol). The combination of the remarkable sensitivity of the CL method with the large number of Ag+ released from each hybrid allows the detection of specific sequence DNA targets at levels as low as 5 fM. The sensitivity increases 6 orders of magnitude greater than that of the gold nanoparticle-based colorimetric method and is comparable to that of surface-enhanced Raman spectroscopy, which is one of the most sensitive detection approaches available to the nanoparticle-based detection for DNA hybridization. Moreover, the perfectly complementary DNA targets and the single-base mismatched DNA strands can be evidently differentiated through controlling the temperature, which indicates that the proposed CL assay offers great promise for single-nucleotide polymorphism analysis. [ABSTRACT FROM AUTHOR]

Ultraviolet resonance Raman spectroscopy is carried out using a continuous wave frequency-doubled argon ion laser operated at 229, 244, and 257 nm in order to characterize the overtones and combination bands for several classes of organic compounds in liquid solutions. Contrary to what is generally anticipated, for molecules such as pyrene and anthracene, strong overtones and combination bands can show up; it is demonstrated that their intensity depends critically on the applied laser wavelength, lithe excitation wavelength corresponds with a purely electronic transition—this applies to a good approximation for 244-nm excitation in the case of pyrene and for 257-nm excitation in the case of anthracene—mostly fundamental vibrations (up to 1700 cm-1) are observed. Overtones and combination bands are detected but are rather weak. However, if the laser overlaps with the vibronic region—as holds for 229- and 257-nm excitation for pyrene and 244-nm excitation for anthracene—very strong bands are found in the region 1700-3400 cm-1. As illustrated for pyrene at 257 nm, all these bands can be assigned to first overtones or binary combinations of fundamental vibrations. Their intensity distribution can roughly be simulated by multiplying the relative intensities of the fundamental bands. Significant bands can also be found in the region 3400-5000 cm-1, corresponding with second overtones and ternary combinations. It is shown that these findings are not restricted to planar and rigid molecules with high symmetry. Substituted pyrenes exhibit similar effects, and relatively strong overtones are also observed for adenosine monophosphate and for abietic acid. The reasons for these observations are discussed, as well as the potential applicability for analytical purposes. [ABSTRACT FROM AUTHOR]

Fast analysis of bioaerosols in clean room environments is necessary in order to prevent contamination of pharmaceutical products, minimize machine downtimes, or both. The detection and identification of microbes will be carried out in several steps: After impaction of the aerosol on a surface, the particles are presorted with glancing light illumination and fluorescence imaging in order to distinguish between abiolic and biotic particles. Since only the biotic particles are of interest, the analysis time can be minimized due to reduction of the data set. The biotic particles are then analyzed further with Raman spectroscopy and identified with a support vector machine. [ABSTRACT FROM AUTHOR]

We report the collection of Raman optical activity (ROA) spectra of adenine in silver colloidal solution, that is, surface-enhanced Raman optical activity (SEROA) using considerably shorter data acquisition times, reduced excitation power, and lower concentration, as compared to classical ROA measurements on molecules of biological interest so far reported in the literature. These improvements in experimental parameters for ROA measurements can be explained by enhanced Raman signals in the local optical fields of the silver nanoparticles and by at least 1 order of magnitude higher values for circular intensity differences (CIDs), as compared to classical ROA that has been suggested before and theoretically discussed in terms of large field gradients near a metal surface. The measured ROA effect for adenine can be understood in terms of adsorption-induced chirality in the prochiral molecules on the silver nanoparticles. Surface-enhanced Raman optical activity offers potential capabilities for sensitive, rapid, stereochemical characterization of basic building blocks of biopolymers, such as amino acids and nucleosides, as well as biologically active molecules, in particular, also for probing organization and self-assembling of such molecules on metal surfaces. [ABSTRACT FROM AUTHOR]

In vivo Raman spectroscopy, using fiber-optic probes is hindered by the intense background signal, which is generated in the fused-silica fibers, in the fingerprint region of the Raman spectrum (∼-0-2000 cm-1). Optical filtering is necessary to obtain tissue spectra of sufficient quality. The complexity of fiber-optic probes for fingerprint Raman spectroscopy, in combination with size constraints and flexibility requirements for in vivo use have been a major obstacle in the development of in vivo diagnostic tools based on Raman spectroscopy. A setup for remote Raman spectroscopic tissue characterization in the high- wavenumber region (∼-2400-3800 cm-1) is presented. It makes use of a single, unfiltered, optical fiber for guiding laser light to the sample and for collecting scattered light and guiding it back to a spectrometer. Such a simple configuration is possible because the fused-silica core and cladding of the fiber present almost no Raman background signal at these wavenumbers. Several commercially available optical fibers were tested with respect to Naman signal background, to determine their suitability for in vivo Raman spectroscopy measurements in the high-wavenumber region. Different fiber core, cladding, and coaling materials were tested. Silica core-silica clad fibers, with an acrylate coaling and a black nylon jacket, proved to be one of the best candidates. In vitro measurements on brain tissue of a 6-month-old pig were obtained with a remote high-wavenumber Raman setup. They illustrate the low background signal generated in the setup and the signal quality obtained with a collection lime of 1 s. [ABSTRACT FROM AUTHOR]

A new, mixed decanethiol (DT)/mercaptohexanol (MH) partition layer with dramatically improved properties has been developed for glucose sensing by surface-enhanced Raman spectroscopy. This work represents significant progress toward our long-term goal of a minimally invasive, continuous, reusable glucose sensor. The DT/MH- functionalized surface has greater temporal stability, demonstrates rapid, reversible partitioning and departitioning, and is simpler to control compared to the tri-(ethylene glycol) monolayer used previously. The data herein show that this DT/MH-functionalized surface is stable for at least 10 days in bovine plasma. Reversibility is demonstrated by exposing the sensor alternately to 0 and 100 mM aqueous glucose solutions (pH∼ 7). The difference spectra show that complete partitioning and departitioning occur. Furthermore, physiological levels of glucose in two complex media were quantified using multivariate analysis. In the first system, the sensor is exposed to a solution consisting of water with 1 mM lactate and 2.5 mM urea. The root-mean-squared error of prediction (RMSEP) is 92.17 mg/dL (5.12 mM) with 87% of the validation points falling within the A and B range of the Clarke error grid. In the second, more complex system, glucose is measured in the presence of bovine plasma. The RMSEP is 83.16 mg/dL (4.62 mM) with 85% of the validation points falling within the A and B range of the Clarke error grid. Finally, to evaluate the real-lime response of the sensor, the lie time constant for glucose partitioning and departitioning in the bovine plasma environment was calculated. The time constant is 28 s for partitioning and 25 s for departitioning, indicating the rapid interaction between the SAM and glucose that is essential for continuous sensing. [ABSTRACT FROM AUTHOR]

We report on a rapid method for reagentless identification and discrimination of single bacterial cells in aqueous solutions using a combination of laser tweezers and confocal Raman spectroscopy (LTRS). The optical trapping enables capturing of individual bacteria in aqueous solution in the focus of the laser beam and levitating the captured cell well off the cover plate, thus maximizing the excitation and collection of Raman scattering from the cell and minimizing the unwanted background from the cover plate and environment. Raman spectral patterns excited by a near-infrared laser beam provide intrinsic molecular information for reageatless analysis of the optically isolated bacterium. In our experiments, six species of bacteria were used to demonstrate the capability of the confocal LTRS in the identification and discrimination between the diverse bacterial species at various growth conditions. We show that synchronized bacterial cells can be well-discriminated among the six species using principal component analyses (PCA). Unsynchronized bacterial cells that are cultured at stationary phases can also be well-discriminated by the PCA, as well as by a hierarchical cluster analysis (HCA) of their Raman spectra. We also show that unsynchronized bacteria selected from random growth phases can be classified with the help of a generalized discriminant analysis (GDA). These findings demonstrate that the LTRS may find valuable applications in rapid sensing of microbial cells in diverse aqueous media. [ABSTRACT FROM AUTHOR]

The King George III copy of the Gutenberg Bible, held at the British Library, has been analyzed using Raman spectroscopy to determine the palette of pigments used in the illuminations on this work. The palette is found to comprise cinnabar/vermilion, lead tin yellow (type 1), carbon-based black, azurite, malachite, an organo-copper complex (a "verdigris"), calcium carbonate (chalk), gyp-sum, gold leaf, and basic lead carbonate ("lead white"). This is in agreement with contemporary descriptions of the pigments used for the illuminations. One pigment could not be identified, specifically the organic dark red/purple color used for the foliage. The palette of this copy of the Gutenberg Bible has been compared with those used for six other copies, held at Eton College and Lambeth Palace, England, the Bibliothèque Mazarine and the Bibliothèque nationale de France, and the Staatsbib- liothek zu Berlin and the Niederskchsische Staats- und Universitätsbibliothek (SUB) Göttingen, Germany. The palettes are shown to be similar to one another, even though the styles of the primary illuminations differ. The two Gutenberg Bibles held in Germany, printed on vellum, have the more expensive palettes, which include lazurite. The SUB Göttingen copy has the most extensive palette with 16 pigment-related materials having been identified. [ABSTRACT FROM AUTHOR]

The structural properties of polyctystalline yttria-stabilized zirconia (YSZ) have been studied using FT-Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy (XPS). Yttria content was varied between 8 and 15% (by mole fraction) to determine compositional effects on YSZ phonon structure, lattice parameter, and oxidation state. The dominant feature in the low-frequency Raman spectrum correlates quite closely with the material's sole (cubic) lattice parameter. XPS measurements of typical YSZ samples show only a single species of both Y and Zr. After exposing YSZ to a reducing environment (H2) at elevated temperatures (1000 °C), however, the XPS spectra of YSZ show new features at lower binding energy for both Y and Zr. Angle-resolved XPS measurements suggest that these reduced forms of Y and Zr exist only within the first few molecular layers of the sample. This treatment does not effect the XRD pattern, nor does it change the low-frequency phonon structure observed in the Raman spectrum, although the Raman spectrum does experience ∼50% reduction in overall signal intensity. These disparities are reconciled with each other based on differences in each technique's sampling depth. The impact that surface-reduced YSZ may have on the chemistry occurring within solid oxide fuel cells is discussed briefly. [ABSTRACT FROM AUTHOR]

Despite its potential, the use of Raman spectroscopy for real-time quantitative reaction monitoring is still rather limited. The problems of fluorescence, laser instability, low intensities, and the inner filter effect often outscore the advantages as narrow bands, the use of glass fibers, and low scattering of water and glass. In this paper, we present real-time quantitative monitoring of the catalyzed Heck reaction by using the solvent as internal standard. In this way, all multiplicative distortions, e.g., laser intensity variations or absorbance of the laser light, can be corrected for. We also show that a limited amount of fluorescence does not hamper the analysis. Finally, we present a new method to correct for the inner filter effect, i.e., the absorbance of Raman scattered light by the reaction medium. Simultaneous absorption measurements of the reaction mixture enable accurate correction of Raman signals for the inner filter effect. Thus, for reaction monitoring applications, a Ranian spectrometer should be equipped with an absorbance measurement device. [ABSTRACT FROM AUTHOR]

A method is presented for the use of SAM layers as internal standards for calibration in surface-enhanced Raman spectroscopy. Three cyano-containing compounds were attached to gold colloids via a metal-sulfur bond and evaluated for spectral stability and normalization capacity. The results show that the analyte, rhodamine 6G, and the internal standard signal enhancement covaried, and it was possible to quantify the analyte with PLS. The fact that the enhancing substrate was chaotic assemblies with large variation in signal enhancement shows the versatility of this method. [ABSTRACT FROM AUTHOR]

Micro-Raman spectroscopy, infrared absorption microspectroscopy, and AFM images of nano- or microsized micelles formed by fulvic acid (PA) solutions, prepared at different pHs, and cast on glass slides or gold island films, are reported. PA films cast on gold islands are characterized by surface-enhanced infrared absorption (SEIRA), surface- enhanced infrared reflection absorption, and surface- enhanced Raman scattering (SERS). Based on spectral evidence, it is expected that the chemisorption of FA on gold island films takes place through thiol groups, which become more active as pH increases. The SEIRA spectra of these films show increased peak intensity, as well as improved band resolution. Microspectroscopy SERS studies show that, at pH 5, FA form small aggregates on gold surfaces. AtpH 8, PA tends to expand due to electrostatic repulsion, giving rise to a fractal surface composed of different domains. SERS studies of these domains reveal that the most polar molecules are located on the external faces. At pH 11, fractal conformations are even more pronounced and give rise to radial patterned structures. At this pH, the position of fulvic acid molecules in the fractal micelles is the same as observed at pH 8. In this way, SERS can be viewed as a powerful tool for the analysis of the composition, apparent contribution of the surface functional groups of FA films, and the FA building blocks (i.e., catechol, gallic, salicylic, or ftalic acids) in the structures of these materials. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman scattering (SERS) utilizing colloidal silver has already been shown to provide a rapid means of generating "whole-organism fingerprints" for use in bacterial identification and discrimination. However, one of the main drawbacks of the technique for the analysis of microbiological samples with optical Raman microspectroscopy has been the inability to acquire pre-emptively a region of the sample matrix where both the SERS substrate and biomass are both present. In this study, we introduce a Raman interface for scanning electron microscopy (SEM) and demonstrate the application of this technology to the reproducible and targeted collection of bacterial SERS spectra. In secondary electron mode, the SEM images clearly reveal regions of the sample matrix where the sodium borohydride-reduced silver colloidal particles are present, Stokes spectra collected from these regions are rich in vibrational bands, whereas spectra taken from other areas of the sample elicit a strong fluorescence response. Replicate SERS spectra were collected from two bacterial strains and show excellent reproducibility both by visual inspection and as demonstrated by principal components analysis on the whole SERS spectra. [ABSTRACT FROM AUTHOR]

Glutamate is the major excitatory neurotransmitter and is of particular interest in light of current models of memory and learning. The paper describes the first in situ detection of glutamate in single nerve terminals (synaptosomes), which is achieved by using laser trapping Raman spectroscopy. The near-infrared laser light captures a single synaptosome obtained from a Wister rat brain. The release of glutamate in a single laser-trapped synaptosome was detected by subtracting the Raman spectrum before depolarization from that after depolarization with the addition of the K+-channel blocker, 4-aminopyridine. The result indicated that the single synaptosome released ∼3 amol of glutamate and that the release rate depended on the 4-aminopyridine concentration. [ABSTRACT FROM AUTHOR]

The principles of quality control and multivariate statistical analysis were applied to the monitoring of the conservation state of wooden works of art. Three degradation processes (exposure to a wet atmosphere, to an acidic attack, and to UV light were simulated on the surface of wooden boards of the XVI century and were monitored by the use of Raman spectroscopy. The resulting spectra were treated by principal component analysis, which allowed reduction of the system dimensionality. The relevant principal components were used to build multivariate control charts, namely, the Shewhart, CUSUM, and SMART (simultaneous scores monitoring and residual tracking) control charts. The Shewhart charts allowed identification of the effects due to the degradation processes. The CUSUM charts permitted identifcation of the exact moment in which the degradation treatment was started. The SMART charts provided a synthetic description of the conservation state of the wooden surface by means of only two charts: the T[SUP2] Hotelling and the DModX charts. [ABSTRACT FROM AUTHOR]

Compares three different Raman microscopic imaging methodologies using a single experimental configuration. Information about these microscopic imaging methodologies; Analysis of Raman imaging data acquired with equivalent low-power laser excitation and a cooled CCD camera; Overview of imaging microscopic system used in this comparison; Highlights of the test sample on which all experiments were carried out.

Studies complexes formed between G-quadruplex (G4)-conformed oligonucleotides and four ethidium derivatives by using the technique Surface-Enhanced Raman Spectroscopy (SERS) to detail the topology of complexes that support a G4 stabilization involving selective interactions of ethidiums with G4 DNA revealed by Surface-Enhanced Raman Scattering . Impact of ethidium bromide (EB) ; Overview of the possible conformation of an intermolecular G4 formed by the human G-rich telomeric repeat; Highlights of the chemical structure of EB and three of its analogues, ethidiums 1-3; Methodology followed for the preparation of silver colloid and acquisition of SERS spectra.

Focuses on a surface-enhanced Raman spectroscopic (SERS) technique for the determination of ions of lead, cadmium and copper concentration using a 4-(2-pyrridylazo)resorcinol (PAR) coating modified with disulfide. Substrate preparation; Selectivity and atomic specificity.

Raman spectroscopy measures molecular vibrations triggered by the inelastic scattering of light, while Raman optical activity (ROA) measures a small difference in the Raman scattering from chiral molecules using circularly polarized light. We used Raman or ROA spectra to determine the secondary structure contents (helix, sheet, or other) of proteins. Forty-four ROA and 24 Raman protein spectra were converted into mean intensities within 10 cm-1 width bins. The partial least squares algorithm with 5-fold cross-validation was used to construct models to give secondary structure contents from spectral data. The optimized algorithm gives highly accurate secondary structure contents, with R2 and rmsd values of 0.99, and 0.6-1.7%, respectively, for second derivative Raman data when comparing predicted to experimental data. Using ROA data from 620 to 1850 cm-1 is almost as accurate. Analysis of amide I, II, and III and backbone spectral regions reveals the importance of each of these regions for secondary structure assignment. Raman and ROA may be the methods of choice for rapid measurement of protein secondary structure contents, since they have unprecedented accuracy. [ABSTRACT FROM AUTHOR]

Surface-enhanced resonance Raman spectra of cytochrome c on silver electrodes coated with self-assembled monolayers of mercaptopropionic acid were recorded at different potentials using 50 μL of a micromolar solution. For this purpose, a linearly moving, low-volume, small spectroelectrochemical cell was designed and used together with a Raman microprobe. The quality of the spectra obtained is good, and the spectra show essentially the same features reported by other authors using much larger volumes. The cell described in this paper is shown to be useful for studying the spectroelectrochemistry of photosensitive compounds such as heme proteins, which are available only in very small amounts (nanomoles to picomoles). [ABSTRACT FROM AUTHOR]

The article reports on the innovation by the researchers at the University of Tennessee on electron-beam lithography (ELB) and nanoTransfer printing (nTP) to control the shape and spacing of surface-enhanced Raman spectroscopy (SERS). It reports that the researchers, Nahla Abu Hatab, Jenny Oran, and Michael Sepaniak, used EBL to build a nTP that can stamp out well-defined arrays of nanoscale silver SERS substrates on PDMS. It reports that SERS is gaining popularity as a technique capable of single-molecule detection that works in conjunction with nanoparticulate or nanstructured noble-metal substrates. It offers information on how the researchers built their innovation and their future plans with SERS.

The article reports on the use of Raman spectroscopy in tracking the circulation of single-walled carbon nanotubes (SWNTs) in mice. The method was developed by Hongjie Dai and colleagues at Stanford University wherein they used SWNTs that are coated with polyethylene glycol (PEG) chains for various lengths and injected it to the mice. They found that SWNTs exhibit an intrinsic Raman scattering intensity that does not decay over time and is unchanged by functionalization of the nanotubes with noncovalent coatings. They also observed that the longer the PEG chain, the longer the SWNTs remained in circulation in the bloodstream. Although there is a significant accumulation of the SWNT in the liver and spleen, the authors note that no toxic effects were observed in the mice.

The article reports on the research that demonstrated that fluorescence microscopy has more limitations than coherent anti-Strokes Raman scattering (CARS) microscopy in imaging lipids in live organisms. The researchers showed that CARS provides information about the various stages of lipid storage with high chemical specificity. It adds that for wild-type nematodes, CARS and fluorescence images of lipid droplets nicely matched but for mutant worms, lipid droplets in hypodermal body-wall cells were barely visible in the fluorescence images.

The article offers information about the adapted spatially offset Raman spectroscopy (SORS), a technique that can question the contents of plastic and glass beverage, medicine, and cosmetic containers. It holds back fluorescence and Raman signals from the walls of the container and offers the Raman spectrum of the ingredients inside. It demands the collection of Raman spectra regions offset from the point of illumination on the sample surface, then by a sealed subtraction of spectra to separate signals from individual layers within the sample. It works on samples with transparent sublayer since the diffusely scattering container serves as a source of diffused radiation for a large area of liquid inside.

The article reports on the use of the confocal nonresonant Raman microspectroscopy to track mitochondrial distribution in cells by Max Diem and colleagues at Northeastern University in Boston, Massachusetts. The report noted that mitochondria are typically visualized by electron microscopy or fluorescence-labeling methods, of which both are at least invasive, and researchers wanted to find a method that could track mitochondria yet would minimally disrupt the intracellular environment. The researchers indicated that although their study was carried out on fixed cells, the use of a water-immersion objective would allow the same procedure to be carried out on live, unlabeled cells noninvasively and in their native environment.

The article discusses the benefits of 3D cluster secondary ion mass spectrometry (SIMS). The technique offers good depth resolution and submicrometer lateral resolution and the very high molecular specificity that mass spectrometry brings. According to researchers, a critical step in reconstructing 3D images is to account for the fact that material may be removed at different rates throughout the sample and they present a way to make corrections. However, techniques in 3D SIMS analysis such as confocal fluorescence microscopy and confocal Raman spectroscopy can be performed in air or water.

The article discusses Raman spectroscopy and fluorescence microscopy and its contribution to the study of cells. In the case of cellular imaging fluorescence microscopy can swiftly image large areas of the cell whereas Raman will present an informed picture of intracellular chemistry. Bringing the two techniques in the same experiment has not proved feasible because orders of magnitude is greater and is usually swamped by the fluorescence signal in Raman scattering. The article presents two methods by researchers for merging the techniques.

The article presents information on single-molecule gap-mode tip-enhanced Raman spectroscopy (TERS). In TERS, a metal tip that is sharp excites localized surface plasmons to make a hot site and further improve the electromagnetic field and Raman signals near the apex of the tip. TERS has applications in areas such as catalysis, bioscience, and nanomaterials. Researchers Renato Zenobi and colleagues at ETH Zurich found out that corrugations on the order of a few nanometers on a surface can develop the signal enhancement in TERS. The investigators adsorbed a benzenethiol monolayer on a gold substrate to find out how corrugations infIuenced TERS signal intensity.

The article discusses the study which seeks to evaluate the limits of the newly designed Raman optical activity (ROA) spectrometer. According to the author, ROA is similar to compact disk (CD) spectroscopy when used to compare the reaction between polarized light and a chiral molecule. He states that both techniques provide information about molecular structure, but ROA spectrum contains more bands and thus more data about fine structural details are obtained. Information about the experiment on ROA spectra for neopentane is presented.

The article reports on the examination of pharmaceutical products to identify inappropriate active pharmaceutical ingredients (API). The spatially offset Raman spectroscopy (SORS) was used and applied by Charlotte Eliasson and Pavel Matousek, who are both from the Rutherford Appleton Laboratory, to identify noninvasive API. The process starts with conventional Raman (CR) spectroscopy, which has limited usefulness in samples that diffusely scatter the laser light. The SORS also reduces the blinding effect of the surface layers and allows clearer observations of the sublayers.

The article describes the use of deep-ultraviolet (UV) wavelengths with resonance Raman spectroscopy for determining the mineral and chemical compositions of three Martian meteorites. Both organic and inorganic components in a heterogeneous system can be detected by a miniaturized Raman spectrometer. The U.S. National Aeronautics and Space Administration and the European Space Agency expressed their interest in the use of the method for the search for extraterrestrial life. There is a perceived competition between the use of UV Raman spectroscopy and GC/MS for the identification of organic molecules in Mars.

The article reports on the findings of Gerwin J. Puppels of Erasmus University Rotterdam, Netherlands, and his colleagues related to the use of Raman spectroscopy in scanning brain tumors and some challenges related to it. Puppels and his colleagues had earlier on described a method based on Raman spectroscopy that promises to be the first step in detecting residual meningioma cells in vivo. This will help surgeons in providing with real-time guidance while operating. The researchers examined two common tumor types and one rare type by looking at 38 tissue samples taken from 20 patients and compared them with known spectra. Then, they collected spectral data and plotted Raman maps. To express their findings, the researchers developed a correlation model that was based on linear discriminant analysis. Puppels and colleagues distinguished dura matter from tumor with an accuracy of 100 percent. Although pure dura and meningioma samples can be identified very well, a surgeon would not have the benefit of gathering pure dura or meningioma spectra. According to Puppel the challenge lies in the fact that one want to be able to detect tumor tissue, even when it makes up only a small fraction of the tissue volume from which a spectrum is recorded.

The article cites a study conducted by researcher Hiro-o Hamaguchi and colleagues published in the 2005 issue of the journal "Biochemistry" which uses a combination of time and space-resolved Raman spectroscopy to track the movements of subcellular organelles in living fission yeast. When a yeast cell divides, the nuclear material is split in two. The resulting nuclei move to opposite ends of the cell, and a septum, which will become the division site, forms at the center. Raman spectroscopy can provide information about the locations of nuclei, mitochondria, cytoplasm and septa within cells. Because mitochondria are small and move quickly, space-resolved Raman measurements sometimes produce spectra with features of multiple organelles. Therefore, Hamaguchi and colleagues combined the technique with time-resolved Raman spectroscopy. A laser beam was fixed at the center of a cell, and measurements were taken throughout the cell cycle. At the beginning of the experiment, a spectrum characteristic of the nucleus was observed.

The article presents information on a protocol for detecting bacillus spores by surface-enhanced Raman spectroscopy (SERS) with a low-cost, battery-powered, portable Raman spectrometer. The protocol was developed by researcher Richard Van Duyne and colleagues at Northwestern University. The speed and sensitivity of the SERS sensor make it applicable for field detection of harmful environmental agents. In laboratory experiments, the researchers extracted the biomarker calcium dipicolinate (CaDPA) from Bacillus subtilis spores, which are harmless simulants of Bacillus anthracis (anthrax). They detected the CaDPA on silver film over nanosphere (AgFON) substrates by SERS.

Researcher Ju´n Perez and colleagues at the Universitat d'Alacant performed surface-enhanced Raman spectroscopy (SERS) on electrodes that were prepared by spontaneously depositing pure platinum or palladium nanoparticles on the surfaces. The researchers say that this "nanoparticle-on-electrode" approach is simpler than electrochemical roughening of electrode surfaces and that it produces high-quality spectra. The researchers speculate that the new approach might make it straightforward to extend SERS studies to alloys of platinum-group metals or to deposit nanopartides with well-defined shapes onto surfaces for SERS analysis.

Reports on the new vibrational spectroscopy tool developed by researcher Richard Mathies and colleagues at the University of California, Berkeley, for studying structural changes during ultrafast chemical and biological reactions as of September 2003. Information about the Femtosecond stimulated Raman spectroscopy; Commonly used techniques for examining structural changes on femtosecond timescales; Demonstration of the new technique by Mathies and colleagues.

Reports on the spectroscopic analysis of the rod-shaped turnip mosaic virus. Virus' ability to infect 20 families of dicotyledonous plants; Determination of its host specificity; Use of surface-enhanced Raman spectroscopy in biological macromolecular studies; Chinese chemists' examination of the secondary structure of the virus coat protein.