Synthesis and characterization of silver nanoparticles for SERS-based biosensing

Abstract

<p>Colloidal silver nanoparticles (AgNPs) were synthesized via reduction of silver nitrate with sodium borohydride using a slightly modified Creighton method. AgNPs were then characterized and using UV-VIS absorption spectrophotometry, transmission electron microscopy (TEM), flame atomic absorption spectroscopy (FAAS), fluorescence spectroscopy, Raman and surface-enhanced Raman spectroscopy. The UV-VIS absorption spectra presented a sharp maximum at 400 nm indicating a minimal aggregation. The TEM images and size histograms prepared by analyzing 400 AgNPs indicated that the AgNPs were spherical with an average diameter of about 11 nm and a narrow size distribution. FAAS data demonstrated a high reaction yield and allowed for the quantification of the amount of AgNPs produced (i.e., 15.31 ppm). Raman spectra helped confirmed the purity of the AgNPs. Surface-enhanced Raman spectroscopy measurements were performed using the rhodamine 6G (R6G) dye at various concentrations to evaluate the sensing efficiency of these colloidal AgNPs. The analytical -(7.3 x 104) and surface-enhanced Raman enhancement factors (5.1 x 101) were calculated based on the Raman, SERS, and fluorescence spectra at a R6G concentration of 10-6 M. In conclusion, the proposed synthesis method led to the formation of colloidal AgNPs of highly uniform size and shape, minimal aggregation and SERS-based biosensing potential similar to other colloidal nanoparticle systems described in the literature.</p><p>This presentation occurred at the Wright State University Campus-Wide Celebration of Research, Scholarship and Creative Activities on April 16, 2010</p>