title: Optical properties of dopamine molecules with silver nanoparticles as surface-enhanced raman scattering (SERS) substrates at different pH conditions.
abstract: Silver nanoparticles (Ag NPs) prepared by the citrate reduction method were examined as surface-enhanced Raman scattering (SERS) substrates in the detection of dopamine (DA) molecules at different hydrogen ion concentrations. The aggregation of Ag NPs was influenced by the crosslinking effect of DA molecules as the function of pH of colloidal solution. Somewhat clustering of Ag NPs in a limited pH range (pH 7-9) exhibited the strong red-shift of absorption peak and maximal SERS activity to DA molecules, highlighting the importance of strong electrostatic adsorption and cross-linking effect that allowed DA molecules to reside in the junctions (hot spots) between aggregated Ag NPs. Furthermore, Ag NPs with DA molecules at strongly basic condition (> pH 9) exhibited the relatively high SERS activity as compared to negligible SERS activity at acidic condition (< or = pH 5), indicating the important role of oxidized surface of silver NPs which can interact with hydroxyl groups of DA molecules.
authors.affiliation: Department of Chemical and Biochemical Engineering, Gachon University, San 65 Bokjeong-dong Soojung-gu, Seongnam City 461-701, South Korea.
authors.forename: Yanru
authors.initials: Y
authors.lastname: Bu
authors.forename: Sang-Wha
authors.initials: SW
authors.lastname: Lee
mesh_terms: D004298:Dopamine / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D053768:Metal Nanoparticles / Q000737:chemistry*; D055095:Optics and Photonics; D012834:Silver / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods*
chemical_list: D012834:Silver; D004298:Dopamine