Surface-enhanced Raman scattering sensor

Reproduced from L. Xuan Quang, et al., A portable surface-enhanced Raman scattering sensor integrated with a lab-on-a-chip for field analysis, Lab on a Chip 8 (2008) 2214-2219, with permission of The Royal Society of Chemistry. 

Nanosize particles (e.g., metals, semiconductors, etc.) are of continuing interest because they possess fascinating catalytic, electronic, and optical properties. Larger particles decorated with smaller nanoparticles on their surface are of interest because of their potential use as heterogeneous catalysts and their relevance in electronic and optical sensor applications as well as surface-enhanced Raman scattering [39,72-75]. 

A large number of possible applications of arrays of nanoparticles on solid surfaces is reviewed in Refs. [23,24]. They include, for example, development of new (elect-ro)catalytical systems for applications as chemical sensors, biosensors or (bio)fuel cells, preparation of optical biosensors exploiting localized plasmonic effect or surface enhanced Raman scattering, development of single electron devices and electroluminescent structures and many other applications. 

C.E. Talley, L. Jusinski, C.W. Hollars, S.M. Lane and T. Huser, Intracellular pH sensors based on surface-enhanced Raman scattering, Anal. Chem., 76(23) (2004) 7064-7068. 

J.M. Bello, V.A. Narayanan, D.L. Stokes and T. Vo-Dinh, Fiber-optic remote sensor for in situ surface-enhanced Raman scattering analysis, Anal. Chem., 62(22) (1990) 2437-2441. 

J.M. Bello and T. Vo-Dinh, Surface-enhanced Raman scattering fiberoptic sensor, Appl. Spectrosc., 44(1) (1990) 63-69. 

In principle, optical chemosensors make use of optical techniques to provide analytical information. The most extensively exploited techniques in this regard are optical absorption and photoluminescence. Moreover, sensors based on surface plasmon resonance (SPR) and surface enhanced Raman scattering (SERS) have recently been devised. 

In the future, we will see developments involving surface enhanced Raman scattering technologies in combination with AuNPs and waveguides as well as combinations of immobilized and solution-bom AuNPs and functional bridges in-between them. It can also be expected that applied medical research, namely the detection of antigens, enzymes, and proteins in body fluids, will benefit fi om the sensor developments with its extreme sensitivities. 

The metallic nanocrystals are remarkable due to their localized surface plasmon resonance (SPR) phenomenon, that is, the excitation of surface plasma by light. It ensures these nanocrystals to be color based sensors (Homola et al., 1999 Kelly et al., 2003). The metallic nanocrystals could also sensitize the Raman signals from their adsorbed organic molecules. This surface enhanced Raman scattering (SERS) effect potentially raises the detection sensitivity to single molecule level (Kneipp et al., 1997 Nie and Emery, 1997). 

Because macroporous materials have 3D periodicity on a length scale comparable to the wavelength of visible light, 3DOM materials have potential use as photonic crystals. Other potential applications include catalysts, bioglasses, sensors, and substrates for surface-enhanced Raman scattering spectroscopy (SERS). ... 

The surface-enhanced Raman scattering (SERS)-active substrates were prepared by electrodeposition of Ag nanoparticles in multiwalled carbon nanotubes (MWCNTs)-based nanocomposites for SERS sensor application. 

Tsai YC, Hsu PC, Lin YW, Wu TM (2009) Silver nanoparticles in multiwalled carbon nanotube-Nafion for surface-enhanced Raman scattering chemical sensor. Sensor Actuator B 138 5-8... 

Zhang Y, Shi C, Gu C, Seballos L, Zhang JZ (2007) Liquid-core photonic crystal fiber sensor based on surface-enhanced Raman scattering. Appl Phys Lett 90 193504... 

Yan F, Vo-Dinh T. (2007) Surface-enhanced Raman scattering detection of chemical and biological agents using a portable Raman integrated tunable sensor. Sens. Actuators B Chem. 121 61-66. 

The phenomenon of surface-enhanced infrared absorption (SEIRA) spectroscopy involves the intensity enhancement of vibrational bands of adsorbates that usually bond through contain carboxylic acid or thiol groups onto thin nanoparticulate metallic films that have been deposited on an appropriate substrate. SEIRA spectra obey the surface selection rule in the same way as reflection-absorption spectra of thin films on smooth metal substrates. When the metal nanoparticles become in close contact, i.e., start to exceed the percolation limit, the bands in the adsorbate spectra start to assume a dispersive shape. Unlike surface-enhanced Raman scattering, which is usually only observed with silver, gold and, albeit less frequently, copper, SEIRA is observed with most metals, including platinum and even zinc. The mechanism of SEIRA is still being discussed but the enhancement and shape of the bands is best modeled by the Bruggeman representation of effective medium theory with plasmonic mechanism pla dng a relatively minor role. At the end of this report, three applications of SEIRA, namely spectroelectrochemical measurements, the fabrication of sensors, and biochemical applications, are discussed. 

Recently, the production of nanofibres using nanocomposites has attracted attention. This is due to the fact that this type of nanofibre combines the unique properties of nanocomposites with the outstanding characteristics of nanofibres. Metal/polymer nanocomposites have not only the potential to meet the requirements of applications such as photonic and electric sensors, filters, and artificial tissue, but also can act as catalysts. Silver nanoparticles are the most common embedded metal nanoparticles used in conjunction with polymers. This is because silver nanoparticles exhibit remarkable properties including catalytic activity, surface-enhanced Raman scattering activity, high electrical conductivity and antimicrobial activity. 

Abstract. Surface-eDhanced Raman scattering is a powerful tool for the investigation of biological samples. Following a brief introduction to Raman and surface-enhanced Raman scattering, several examples of biophotonic applications of SERS are discussed. The concept of nanoparticle-based sensors using SERS is introduced and the development of these sensors is discussed. 

Talley, C.E., et al.. Intracellular pH Sensors Based on Surface-Enhanced Raman Scattering. Anal. 

Additional projects in this theme area include Raman measurements of ant-freeze protein, optical measurements of protein folding and collapse, surfaced enhanced Raman scattering (SERS) nanoparticle sensors see the chapter Talley et al) for intracellular measurements, and photocatalytic nanolithography for molecular scale patterning. 

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