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Akram Abbasi1 Geoffrey Bothun1 Arijit Bose1

1, Chemical Engineering, University of Rhode Island, Kingston, Rhode Island, United States

Surface Enhanced Raman Scattering (SERS) is a powerful tool for detection of analytes at low concentrations. To enhance the Raman signal, the analyte must be in close proximity to the substrate. This often requires customization of substrate, making it useful for the detection of only a specific subset of molecules. We have produced hybrid carbon-gold nanoparticles for the detection of a broad spectrum of molecules using Surface Enhanced Raman Scattering (SERS). Carboxyl-terminated carbon black (CB) nanoparticles were coated with the cationic polyelectrolyte poly-L-lysine (PLL), and exposed to a tetrachloroauric acid solution. Gold-carbon black (Au-PLLCB) particles were formed by the reduction of gold chloride ions that concentrate on the surfaces of the PLL-coated CB templates. The Au-PLLCB particles produced strong SERS signals for 4-nitrobenzene thiol (4-NBT) in ethanol, and for Congo red, crystal violet, and nitrate ions in water. The fractal morphology of the carbon black template and the presence of PLL promote the formation of sharp gold spikes on the surface, yielding hot spots for Raman enhancement. The underlying carbon acts as an absorbent for organic molecules, allowing analytes with poor affinity for the gold surface to concentrate in regions close enough to the particle surfaces to enable detection by SERS. The morphology and chemical nature of the underlying template make the Au-PLLCB a broadly applicable type of particle for detecting of a wide range of analytes in solution.

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