Spectroscopy 

About: Spectroscopy is an academic journal. The journal publishes majorly in the area(s): Raman spectroscopy & Mass spectrometry. Over the lifetime, 1261 publications have been published receiving 12997 citations. The journal is also known as: spectrum analysis & spectral analysis.

Surface plasmon resonance: principles, methods and applications in biomedical sciences

Abstract: Surface plasmon resonance (SPR) is a phenomenon occuring at metal surfaces (typically gold and silver) when an incident light beam strikes the surface at a particular angle. Depending on the thickness of a molecular layer at the metal surface, the SPR phenomenon results in a graded reduction in intensity of the reflected light. Biomedical applications take advantage of the exquisite sensitivity of SPR to the refractive index of the medium next to the metal surface, which makes it possible to measure accurately the adsorption of molecules on the metal surface and their eventual interactions with specific ligands. The last ten years have seen a tremendous development of SPR use in biomedical applications. The technique is applied not only to the measurement in real-time of the kinetics of ligand-receptor interactions and to the screening of lead compounds in the pharmaceutical industry, but also to the measurement of DNA hybridization, enzyme-substrate interactions, in polyclonal antibody characterization, epitope mapping, protein conformation studies and label-free immunoassays. Conventional SPR is applied in specialized biosensing instruments. These instruments use expensive sensor chips of limited reuse capacity and require complex chemistry for ligand or protein immobilization. Our laboratory has successfully applied SPR with colloidal gold particles in buffered solution. This application offers many advantages over conventional SPR. The support is cheap, easily synthesized, and can be coated with various proteins or protein-ligand complexes by charge adsorption. With colloidal gold, the SPR phenomenon can be monitored in any UV-vis spectrophotometer. For high-throughput applications, we have adapted the technology in an automated clinical chemistry analyzer. This simple technology finds application in label-free quantitative immunoassay techniques for proteins and small analytes, in conformational studies with proteins as well as in the real-time association-dissociation measurements of receptor-ligand interactions, for high-throughput screening and lead optimization.

The potential of Raman microscopy and Raman imaging in plant research

Abstract: To gain a better understanding on structure, chemical composition and properties of plant cells, tissues and organs several microscopic, chemical and physical methods have been applied during the last years. However, a knowledge gap exists about the location, quantity and structural arrangement of molecules in the native sample or what happens on the molecular level when samples are chemically or mechanically treated or how they respond to mechanical stress. These questions need to be answered to optimise utilization of plants in food industry and pharmacy and to understand structure-function relationships of plant cells to learn from natures unique. Advances in combining microscopy with Raman spectroscopy have tackled this problem in a non-invasive way and provide chemical and structural information in situ without any staining or complicated sample preparation. In this review the different Raman techniques (e.g. near infrared Fourier Transform Raman spectroscopy (NIR-FT), resonance Raman spectroscopy, surface-enhanced Raman spectroscopy) are briefly described before approaches in plant science are summarised. Investigations on structural cell wall components, valuable plant substances, metabolites and inorganic substances are included with emphasis on Raman imaging. The introduction of the NIR-FT-Raman technique led to many applications on green plant material by eliminating the problem of sample fluorescence. For mapping and imaging of whole plant organs (seeds, fruits, leaves) the lateral resolution (~10 μm) of the NIR-FT technique is adequate, whereas for investigations on the lower hierarchical level of cells and cell walls the high resolution gained with a visible laser based system is needed. Examples on high resolution Raman imaging are given on wood cells, showing that changes in chemistry and orientation can be followed within and between different cell wall layers having dimensions smaller than 1 μm. In addition imaging the distribution of amorphous silica is shown on horsetail tissue, including an area scan from a cross section as well as a depth profiling within a silica rich knob of the outer stem wall.

Biomedical applications of Raman and infrared spectroscopy to diagnose tissues

Abstract: The objective of the article is to review biomedical applications which became possible after the development of sensitive and high throughput Raman and Fourier transform infrared spectrometers in the past decade. Technical aspects of the instrumentation are briefly described. Then the broad range of vibrational spectroscopic applications with the focus on imaging and fiber-optical methods are discussed to study mineralized tissue (bone, teeth), skin, brain, the gastrointestinal tract (mouth, pharynx, esophagus, colon), breast, arteries, cartilage, cervix uteri, the urinary tract (prostate, bladder), lung, ocular tissue, liver, heart and spleen. Experimental studies are summarized demonstrating the possibilities and prospects of these methods in various fields of biodiagnostics to detect and characterize diseases, tumors and other pathologies. Infrared (IR) and Raman spectroscopy have recently been applied to address various biomedical is- sues. The basis for these applications is that IR and Raman spectroscopy are vibrational spectroscopic techniques capable of providing details of the chemical composition and molecular structures in cells and tissues. In principle, diseases and other pathological anomalies lead to chemical and structural changes on the molecular level which also change the vibrational spectra and which can be used as sensitive, phenotypic markers of the disease. As these spectral changes are very specific and unique, they are also called fingerprint. The advantages of the methods include that they are non-destructive and do not require extrinsic contrast-enhancing agents. Early reports in the literature regarding the utility of IR and Raman spectroscopy to biomedical problems were based on macroscopic acquisition of spectral data only at sin- gle points which required an a priori knowledge of the location or a pre-selection of the probed position. Since the inhomogeneous nature of tissue was not considered in these early studies, an accurate corre- lation between the histopathology of the sampled area and the corresponding spectra was not possible. Therefore, many of the early results were spurious and they will not be presented here. Considerable progress was made in the past ten years because high throughput and more sensitive instruments be- came available for Raman and IR microspectroscopic imaging. They enable to microscopically collect larger number of spectra from larger sample populations in less time, improving statistical significance and spatial specificity. Simultaneously, fiber-optical probes have been developed for in vivo applications.

In situ Characterisation of Living Cells by Raman Spectroscopy

Abstract: We report the first Raman spectra of individual living and dead cells (MLE-12 line) cultured on bioinert standard poly-L-lysine coated fused silica and on bioactive 45S5 Bioglass R � measured at 785 nm laser excitation. At this excitation wavelength no damage was induced to the cells even after 40 minutes irradiation at 115 mW power, as indicated by cell morphology observation and trypan blue viability test. We show that shorter wavelength lasers, 488 nm and 514 nm, cannot be used because they induce damage to the cells at very low laser powers (5 mW) and short irradiation times (5-20 minutes). The most important differences between the spectra of living and dead cells are in the 1530-1700 cm −1 range, where the dead cells have strong peaks at 1578 cm −1 and 1607 cm −1 . Other differences occur around the DNA peak at 1094 cm −1 .O ur study establishes the feasibility of using the 785 nm laser for an in situ real-time non-invasive method to follow biological events (proliferation, differentiation, cell death, etc.) within individual cells cultured on bioactive scaffolds in their physiologic environment over long periods of time.

Structural Characterization of Lignin and Its Degradation Products with Spectroscopic Methods

Abstract: Lignin is highly branched phenolic polymer and accounts 15–30% by weight of lignocellulosic biomass (LCBM). The acceptable molecular structure of lignin is composed with three main constituents linked by different linkages. However, the structure of lignin varies significantly according to the type of LCBM, and the composition of lignin strongly depends on the degradation process. Thus, the elucidation of structural features of lignin is important for the utilization of lignin in high efficient ways. Up to date, degradation of lignin with destructive methods is the main path for the analysis of molecular structure of lignin. Spectroscopic techniques can provide qualitative and quantitative information on functional groups and linkages of constituents in lignin as well as the degradation products. In this review, recent progresses on lignin degradation were presented and compared. Various spectroscopic methods, such as ultraviolet spectroscopy, Fourier-transformed infrared spectroscopy, Raman spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy, for the characterization of structural and compositional features of lignin were summarized. Various NMR techniques, such as 1H, 13C, 19F, and 31P, as well as 2D NMR, were highlighted for the comprehensive investigation of lignin structure. Quantitative 13C NMR and various 2D NMR techniques provide both qualitative and quantitative results on the detailed lignin structure and composition produced from various processes which proved to be ideal methods in practice.