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SERS Substrates (ser + substrate)
Selected AbstractsMultifunctional Au-Coated TiO2 Nanotube Arrays as Recyclable SERS Substrates for Multifold Organic Pollutants DetectionADVANCED FUNCTIONAL MATERIALS, Issue 17 2010Xuanhua Li Abstract A multifunctional Au-coated TiO2 nanotube array is made via synthesis of a TiO2 nanotube array through a ZnO template, followed by deposition of Au particles onto the TiO2 surface using photocatalytic deposition and a hydrothermal method, respectively. Such arrays exhibit superior detection sensitivity with high reproducibility and stability. In addition, due to possessing stable catalytic properties, the arrays can clean themselves by photocatalytic degradation of target molecules adsorbed to the substrate under irradiation with UV light into inorganic small molecules using surface-enhanced Raman spectroscopy (SERS) detection, so that recycling can be achieved. Finally, by detection of Rhodamine 6G (R6G) dye, herbicide 4-chlorophenol (4-CP), persistent organic pollutant (POP) dichlorophenoxyacetic acid (2,4-D), and organophosphate pesticide methyl-parathion (MP), the unique recyclable properties indicate a new route in eliminating the single-use problem of traditional SERS substrates and show promising applications for detecting other organic pollutants. [source] Engineering Nanoparticle Cluster Arrays for Bacterial Biosensing: The Role of the Building Block in Multiscale SERS SubstratesADVANCED FUNCTIONAL MATERIALS, Issue 16 2010Linglu Yang Abstract Noble metal nanoparticle cluster arrays (NCAs) are a novel class of engineered substrates for surface enhanced Raman spectroscopy (SERS), in which the noble metal nanoparticles interact on multiple length scales to create a multiscale E-field cascade enhancement. In this work the role of the building block for the NCA performance is quantified. Periodic NCAs with constant cluster diameter (D = 200 nm) but variable nanoparticle diameter (d) and intercluster separation (,) were assembled on glass and their optical response and SERS enhancement were systematically characterized as a function of D, ,, and d. An increase of d from 40 to 80 nm and simultaneous decrease of , from 200 to 50 nm led to an improvement of the ensemble averaged SERS enhancement factor by a factor of up to ,8. The coefficient of variation (cv) of the enhancement factors (G) is significantly lower for the d = 80 nm NCAs than for the d = 40 nm and d = 60 nm NCAs. Optimized (D = 200 nm, , = 50 nm, d = 80 nm) NCAs show the overall highest signal reproducibility of all investigated NCAs and random nanoparticle substrates and achieve effective single cell detection sensitivity. [source] Nanostructured gold surfaces as reproducible substrates for surface-enhanced Raman spectroscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 3 2007M. Sackmann Abstract Raman spectroscopy is a common tool for the qualitative and quantitative chemical analysis of molecules. Although the unique identification of molecules is possible via their vibrational lines, high concentrations (mmol/l) are needed for their nonresonant excitation owing to their low scattering cross section. The intensity of the Raman spectra is amplified by the use of the surface-enhanced Raman scattering (SERS) technique. While the use of silver sols results only in a limited reproducibility of the Raman line intensities, lithographically designed, nanostructured gold surfaces used as SERS-active substrates should, in principle, combine the high sensitivity with better reproducibility. For this purpose, we have produced gratings of gold dots on Si(001) surfaces by means of electron beam lithography. Qualitative and quantitative investigations of crystal violet (CV) performed using nanostructured surfaces give high reproducibility and enhancement of the Raman lines. The substrates are reusable after cleaning; all results presented could be obtained from a single SERS substrate. For the experiments very low laser powers were used. Copyright © 2006 John Wiley & Sons, Ltd. [source] Surface-enhanced Raman sensors: early history and the development of sensors for quantitative biowarfare agent and glucose detectionJOURNAL OF RAMAN SPECTROSCOPY, Issue 6-7 2005Christy L. Haynes Abstract Surface-enhanced Raman spectroscopy (SERS) is a powerful technique for the sensitive and selective detection of low-concentration analytes. This paper includes a discussion of the early history of SERS, the concepts that must be appreciated to optimize the intensity of SERS and the development of SERS-based sensors. In order to achieve the lowest limits of detection, both the relationship between surface nanostructure and laser excitation wavelength, as well as the analyte/surface binding chemistry, must be carefully optimized. This work exploits the highly tunable nature of nanoparticle optical properties to establish the first set of optimization conditions. The SERS enhancement factor, EFSERS, is optimized when the energy of the localized surface plasmon resonance (LSPR) lies between the energy of the excitation wavelength and the energy of the vibrational band of interest. With the narrow LSPRs used in this work, it is straightforward to achieve EFSERS , 108. These optimization conditions were exploited to develop SERS-based sensors for two important target molecules: a Bacillus anthracis biomarker and glucose in a serum protein mixture. Using these optimized film-over-nanosphere surfaces, an inexpensive, portable Raman spectrometer was used successfully to detect the infectious dose of Bacillus subtilis spores with only a 5-s data collection. The biomarker used to detect the Bacillus subtilis spores binds irreversibly to SERS substrates, whereas other important biomolecules, such as glucose, do not have any measurable binding affinity to a bare silver surface. To overcome this difficulty, a biocompatible partition layer was self-assembled on the SERS substrate before exposure to the analyte solution. Using the partition layer approach to concentrate glucose near the SERS-active substrate, physiological glucose concentrations can be detected even in the presence of interfering serum proteins. Copyright © 2005 John Wiley & Sons, Ltd. [source] Multifunctional Au-Coated TiO2 Nanotube Arrays as Recyclable SERS Substrates for Multifold Organic Pollutants DetectionADVANCED FUNCTIONAL MATERIALS, Issue 17 2010Xuanhua Li Abstract A multifunctional Au-coated TiO2 nanotube array is made via synthesis of a TiO2 nanotube array through a ZnO template, followed by deposition of Au particles onto the TiO2 surface using photocatalytic deposition and a hydrothermal method, respectively. Such arrays exhibit superior detection sensitivity with high reproducibility and stability. In addition, due to possessing stable catalytic properties, the arrays can clean themselves by photocatalytic degradation of target molecules adsorbed to the substrate under irradiation with UV light into inorganic small molecules using surface-enhanced Raman spectroscopy (SERS) detection, so that recycling can be achieved. Finally, by detection of Rhodamine 6G (R6G) dye, herbicide 4-chlorophenol (4-CP), persistent organic pollutant (POP) dichlorophenoxyacetic acid (2,4-D), and organophosphate pesticide methyl-parathion (MP), the unique recyclable properties indicate a new route in eliminating the single-use problem of traditional SERS substrates and show promising applications for detecting other organic pollutants. [source] Nanoporous Copper with Tunable Nanoporosity for SERS ApplicationsADVANCED FUNCTIONAL MATERIALS, Issue 8 2009Lu-Yang Chen Abstract Nanostructured materials with designable microstructure and controllable physical and chemical properties are highly desired for practical applications in nanotechnology. In this article, it is reported that nanoporous copper with a tunable nanopore size can be fabricated by controlling the dealloying process. The influence of acid concentration and etching potential on the formation of nanoprosity is systematically investigated. With optimal etching conditions, the nanopore sizes can be tailored from ,15 to ,120,nm by controlling the dealloying time. It is found that the tunable nanoporosity leads to significant improvements in surface-enhanced Raman scattering (SERS) of nanoporous copper and peak values of SERS enhancements for both rhodamine 6G and crystal violet 10B molecules are observed at a pore size of ,30,50,nm. This study underscores the effect of complex three-dimensional nanostructures on physical and chemical properties and is helpful in developing inexpensive SERS substrates for sensitive instrumentations in molecular diagnostics. [source] Highly Surface-roughened "Flower-like" Silver Nanoparticles for Extremely Sensitive Substrates of Surface-enhanced Raman ScatteringADVANCED MATERIALS, Issue 45 2009Hongyan Liang Abstract Surface-enhanced Raman scattering (SERS) is a new optical spectroscopic analysis technique with potential for highly sensitive detection of molecules. Recently, many efforts have been made to find SERS substrates with high sensitivity and reproducibility. In this Research News article, we provide a focused review on the synthesis of monodispersed silver particles with a novel, highly roughened, "flower-like" morphology by reducing silver nitrate with ascorbic acid in aqueous solutions. The nanometer-scale surface roughness of the particles can provide several hot spots on a single particle, which significantly increases SERS enhancement. The incident polarization-dependent SERS of individual particles is also studied. Although the different "hot spots" on a single particle can have a strong polarization dependency, the total Raman signals from an individual particle usually have no obvious polarization dependency. Moreover, these flower-like silver particles can be measured by SERS with high enhancement several times, which indicates the high stability of the hot spots. Hence, the flower-like silver particles here can serve as highly sensitive and reproducible SERS substrates. [source] Silver-bacterial cellulosic sponges as active SERS substratesJOURNAL OF RAMAN SPECTROSCOPY, Issue 4 2008Paula A. A. P. Marques Abstract Synthetic Ag-bacterial cellulose nanocomposites are reported here and their performance as surface enhanced Raman scattering (SERS) substrates was investigated using thiosalicylic acid and 2,2,-dithiodipyridine as analytes. These nanocomposite materials act as natural sponges when immersed in aqueous or ethanolic solutions allowing capture and SERS detection of certain dissolved molecules. The detection limits for the above organic analytes reached concentrations as low as 10,4 mol·dm,3 and are considerably lower than the conventional vegetable cellulose analogs. Furthermore, we anticipate that the use of these nanocomposites has a beneficial consequence for the development of handy and active cellulosic SERS substrates, in particular for bioanalysis, as we experimentally demonstrated by testing the amino acids L -phenylalanine, L -glutamin and L -histidine. Copyright © 2008 John Wiley & Sons, Ltd. [source] Fabrication of a range of SERS substrates on nanostructured multicore optical fibresJOURNAL OF RAMAN SPECTROSCOPY, Issue 4 2007D. J. White Abstract An effective method for producing arrays of nanoscale triangles, rods and wells on the distal end of a silica optical fibre is presented. The structures are produced by applying a wet-etch procedure to drawn-down imaging fibres. Structural variation is achieved by altering the final diameter of the drawn fibre. Feature sizes of less than 100 nm can be readily achieved in this way. When coated with silver, surface-enhanced Raman scattering enhancement factors of over 106 can be achieved, depending on the size and shape of the structures present. Copyright © 2006 John Wiley & Sons, Ltd. [source] Surface-enhanced Raman sensors: early history and the development of sensors for quantitative biowarfare agent and glucose detectionJOURNAL OF RAMAN SPECTROSCOPY, Issue 6-7 2005Christy L. Haynes Abstract Surface-enhanced Raman spectroscopy (SERS) is a powerful technique for the sensitive and selective detection of low-concentration analytes. This paper includes a discussion of the early history of SERS, the concepts that must be appreciated to optimize the intensity of SERS and the development of SERS-based sensors. In order to achieve the lowest limits of detection, both the relationship between surface nanostructure and laser excitation wavelength, as well as the analyte/surface binding chemistry, must be carefully optimized. This work exploits the highly tunable nature of nanoparticle optical properties to establish the first set of optimization conditions. The SERS enhancement factor, EFSERS, is optimized when the energy of the localized surface plasmon resonance (LSPR) lies between the energy of the excitation wavelength and the energy of the vibrational band of interest. With the narrow LSPRs used in this work, it is straightforward to achieve EFSERS , 108. These optimization conditions were exploited to develop SERS-based sensors for two important target molecules: a Bacillus anthracis biomarker and glucose in a serum protein mixture. Using these optimized film-over-nanosphere surfaces, an inexpensive, portable Raman spectrometer was used successfully to detect the infectious dose of Bacillus subtilis spores with only a 5-s data collection. The biomarker used to detect the Bacillus subtilis spores binds irreversibly to SERS substrates, whereas other important biomolecules, such as glucose, do not have any measurable binding affinity to a bare silver surface. To overcome this difficulty, a biocompatible partition layer was self-assembled on the SERS substrate before exposure to the analyte solution. Using the partition layer approach to concentrate glucose near the SERS-active substrate, physiological glucose concentrations can be detected even in the presence of interfering serum proteins. Copyright © 2005 John Wiley & Sons, Ltd. [source] | ||||||||||