Analytical Sciences

Abstract − Analytical Sciences, 25(3), 347 (2009).

Surface-enhanced Raman Scattering for Immunoassay Based on the Biocatalytic Production of Silver Nanoparticles
Jiwei CHEN, Yan LUO, Yi LIANG, Jianhui JIANG, Guoli SHEN, and Ruqin YU
State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, P. R. China
We have reported on a novel enzyme immunoassay method for the detection of protein using biocatalytic silver nanoparticles as an enhanced substrate based on surface-enhanced Raman scattering (SERS). First, ascorbic acid was converted from ascorbic acid 2-phosphate by alkaline phosphatase immobilized on polystyrene microwells after a typical sandwich immunoreaction. Then Ag(I) ions were reduced to silver nanoparticles by the obtained ascorbic acid, which would result in a SERS signal when Raman dyes were absorbed. Using human IgG as a model protein, a wide linear dynamic range (1 to 100 ng ml-1) was reached with a low detection limit (0.02 ng ml-1) under the optimized assay conditions. Moreover, the production of an enhanced substrate was chosen as the signaling element in this method, which demonstrates a new way for SERS-based quantitative detection. These results suggest that the application of SERS enhanced by biocatalytic production of metal nanopaticles holds a promising potential for a sensitive immunoassay.