Medical University of South Carolina

Anand M Gole

Catherine J Murphy

Christopher J Orendorff

Tapan Kumar Sau

Tapan K Sau

Surface enhanced Raman scattering (SERS) spectra of 4-mercaptobenzoic acid (4-MBA) self-assembled monolayers (SAMs) on gold substrates is presented for SAMs onto which gold nanoparticles of various shapes have been electrostatically immobilized. SERS spectra of 4-MBA SAMs are enhanced in the presence of immobilized gold nanocrystals by a factor of 10-10relative to 4-MBA in solution. Large enhancement factors are a likely result of plasmon coupling between the nanoparticles (localized surface plasmon) and the smooth gold substrate (surface plasmon polariton), creating large localized electromagnetic fields at their interface, where 4-MBA molecules reside in this sandwich architecture. Moreover, enhancement factors depend on nanoparticle shape, and vary by a factor of 10.

Surface enhanced Raman spectroscopy using shaped gold nanoparticles

In one aspect, the invention relates to methods for enhancing a Raman signal comprising the steps of providing a sample comprising a metal surface, an analyte adhered to the surface, and a metallic nanoparticle coupled to the surface, wherein the nanoparticle has a plasmon resonance band; exposing the sample to incident energy of an excitation wavelength; and detecting the Raman signal of the analyte. In a further aspect, the invention relates to a compositiion comprising a metal surface, a functionalized self-assembled monolayer adhered to the surface, wherin the self-assembled monolayer comprises an analyte, and a cetyltrimethylammonium halide-capped metallic nanoparticle coupled to the surface. In a further aspect, the invention relates to a cetyltrimethylammonium bromide-capped gold nanoparticle and a method for preparing same. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present invention.

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Columbia, SC, United States of America

Anand M Gole