(203f) Highly Sensitive Detection of Antibody as An Indicator of Virus Exposure by Surface-Enhanced Raman Scattering (SERS) Spectroscopy

A rapid, highly sensitive, reproducible and point-of-care Surface-enhanced Raman scattering-based immunoassay system using gold nanoparticles (AuNPs) and dye-labeled protein A/G has been developed. In our system, the capture antigen is chemisorbed on gold nanoparticles (AuNPs), followed by incubating with the testing serum, which may contain the antibodies specific to the antigen. The Raman reporter is then added into the system. This reporter is fabricated by conjugating the dye molecule Malachite green to protein A/G which specifically recognizes and binds to the IgGs. The antibody links antigen covered AuNPs and Protein A/G conjugated reporters together to form a sandwich complex, bringing dye and Au surface in close proximity and initiating SERS effect. A characteristic signal of Malachite green indicates the existence of target antibody. This SERS-based immunoassay is applied to the detection of WNV specific antibody in immunosera, which is an indicator of exposure to WNV Virus. A quantitative curve is obtained by plotting the area of the SERS signal of Malachite Green at 1172 cm-1 and 1218 cm-1 versus the concentration of the immunosera against WNV antigen. In this immunoassay, the detection limit was 2 ng/ml of immunoserum which corresponds to at most 2 pg/ml of WNV specific IgG. This reported SERS-based immunoassay provides a rapid, highly sensitive, portable and cost effective viremia diagnostic tool as an alternative to time-consuming and labor-intensive methods restricted to analytical laboratories.