Applications of SERS-Spectroscopy

The application of SERS spectroscopy to molecules of biological significance... 

B. Sagmuller, B. Schwarze, G. Brehm, S. Schneider, Application of SERS spectroscopy to the identificationof (3, 4-methylenedioxy)amphetamine in forensic samples utilizing matrixstabi-... 

In addition to the many applications of SERS, Raman spectroscopy is, in general, a usefiil analytical tool having many applications in surface science. One interesting example is that of carbon surfaces which do not support SERS. Raman spectroscopy of carbon surfaces provides insight into two important aspects. First, Raman spectral features correlate with the electrochemical reactivity of carbon surfaces this allows one to study surface oxidation [155]. Second, Raman spectroscopy can probe species at carbon surfaces which may account for the highly variable behaviour of carbon materials [155]. Another application to surfaces is the use... 

The label-free detection of biomolecules is another promising field of application for SERS spectroscopy. Tiniest amounts of these molecules can be adsorbed by specific interactions with receptors immobilized on SERS-active surfaces. They can then be identified by their spectra, or specific interactions can be distinguished from unspecific interactions by monitoring characteristic changes in the conformation sensitive SERS spectra of the receptors. 

Fortunately, in favorable cases enhancement mechanisms operate which increase the signal from the interface by a factor of 105 — 106, so that spectra of good quality can be observed - hence the name surface-enhanced Raman spectroscopy (SERS). However, these mechanisms seem to operate only on metals with broad free-electron-like bands, in particular on the sp metals copper, silver and gold. Furthermore, the electrodes must be roughened on a microscopic scale. These conditions severely limit the applicability of Raman spectroscopy to electrochemical interfaces. Nevertheless, SERS is a fascinating phenomenon, and though not universally applicable, it can yield valuable information on many interesting systems, and its usefulness is expected to increase as instrumentation and preparation techniques improve. 

This chapter is divided into two sections. Section 6.1 is concerned with applications of Raman spectroscopy to biochemistry. Related topics to this section are found in Section 3.3.3 of Chapter 3 (SER spectra of dipeptides) and Section 4.1.2 of Chapter 4 (Raman (RR) spectra of peptides, proteins, porphyrins, enzymes and nucleic acids), Section 6.2 describes medical applications of Raman spectroscopy as analytical and diagnostic tools. In contrast to biochemical samples discussed in the former section, medical samples in the latter section contain a number of components such as proteins, nucleic acids, carbohydrates and lipids, etc. Thus, Raman spectra of medical samples are much more complex and must be interpreted with caution. 

Results will be split into various sections the first of which will be fundamentals of hot spots. This will include a summary of the most important developments in the theory of SERS hot spots for both the EM and CT enhancement mechanisms. The second section will cover developments in tip-enhanced Raman spectroscopy (TERS) which represents the idealized hot spot. Then some issues regarding hot spots and the single molecule will be tackled such as the magnitude of enhancement required for single-molecule detection, the effects of molecular orientation with respect to the hot spot as well as the possible influence of optical forces. Sections 4.4 and 4.5 will cover developments in the imaging and fabrication of SERS hot spots, respectively, which have important implications for theoretical modeling as well control of SERS hot spots. The chapter will conclude by summarizing some of the applications of SERS hot spots that have been recently reported. 

Hudson, S.D. and Chumanov, G. (2009) Bioanalytical applications of SERS (surface-enhanced Raman spectroscopy). Analytical and Bioanalytical Chemistry, 394, 679-686. 

Raman scattering spectroelectrochemical investigations can be carried out for polymers deposited at practically any electrode used in electrochemical investigations (platinum, ITO, glassy carbon and others). In addition, successful application of SERS (surface enhanced Raman spectroscopy) for polypyrrole [124] and polythiophene [117] allows for Raman spectroscopic studies of extremely thin layers of conjugated polymers. Raman spectra of conjugated polymers are sometimes obscured by strong fluorescence. This problem can be effectively resolved by the... 

For studies by Raman spectroscopy of biomolecules, which are often not available in large amounts, SERS and RRS can be used. Raman spectra of molecules with a solubility even lower than 5X10 g per 100 g H2O can be obtained by means of SERS. In the case of biopolymers with chromophoric groups, Raman bands are both resonance and surface enhanced and high-resolution Raman spectra from very dilute solutions down to 10 mol 1 can be measured. Summaries of biochemical and biomedical applications of Raman spectroscopy are given in [35] and [36]. A review of pharmaceutical applications of Raman spectroscopy is given in [37]. 

As a first example for illustrating the application of Raman spectroscopy in characteri2ing the orientation of surface species, we consider pyridine adsorption on an Ag surface [84], for several reasons. The first SERS experiment was carried out using pyridine as the adsorbed species. Secondly, pyridine has a large Raman cross section, relatively simple molecular structure, and a good assignment of bands appearing in its normal Raman spectrum and SER spectrum. Thirdly, pyridine is an excellent model molecule for surface coordination studies. Eourthly, interactions of the pyridine molecule with the metal surface involve both the it and lone-pair electrons. 

SERS incorporates most of the advantages of Raman spectroscopy. The greatest benefits are enhanced sensitivity (10 M, ng level), selectivity and surface specificity. However, the great analytical potential for SERS is limited by several factors, amongst which the need for adsorbates on a limited number of metal surfaces [430]. Quantitative applications of SERS are difficult [431]. For SERS to... 

See also Biochemical Applications of Fluorescence Spectroscopy Biomacromolecular Applications of UV-Visible Absorption Spectroscopy Chiroptical Spectroscopy, General Theory Chiroptical Spectroscopy, Orientated Molecules and Anisotropic Systems Ellipsometry Surface Plasmon Resonance, Instrumentation Surface Plasmon Resonance, Theory Surface-enhanced Raman Scattering (SERS), Applications. 

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