CHED 1451 |
| Colloidal gold nanoparticles (15-20 nm diameter) were synthesized by thiosulfate reduction of aqueous HAuCl4 and used for surface enhanced Raman scattering (SERS) studies of a variety of amino acids and fluorescent dyes. The nanoparticles were characterized by UV-vis-NIR absorption spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM). Surface chemistry was confirmed using X-ray photoelectron spectroscopy (XPS). Nanoparticle aggregation was controlled by addition of a stabilizing agent (e.g., Na2SO4) during synthesis. The stabilizing anion was found to play a key role in SERS activity, preventing premature nanoparticle aggregation and mediating the analyte-nanoparticle interaction. Addition of cationic analytes resulted in immediate nanoparticle aggregation and analyte adsorption onto the nanoparticles, as evidenced by appearance of a SERS signal. Analytes containing an easily accessible, positively charged nitrogen exhibited the strongest SERS signals due to favorable electrostatic interactions with the stabilizing anion that encouraged adsorption of the analyte onto the nanoparticle surface. |
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Undergraduate Research Poster Session: Physical Chemistry
2:00 PM-4:00 PM, Monday, March 26, 2007 Hyatt Regency Chicago -- Riverside Center, Poster
Division of Chemical Education |