SERS quantitative detection of trace human chorionic gonadotropin using a label-free Victoria blue B as probe in the aggregated immunonanogold sol substrate.

Abstract

Nanogold particles (NG) were modified by anti-rabbit antibody (RAb) against human chorionic gonadotropin to obtain an immunonanogold probe (ING). In pH 7.0 Na2HPO4-citrate buffer solution containing KCl, ING probes formed large aggregates in which Victoria blue B (VBB) molecules were adsorbed on the surface and which exhibited strong surface-enhanced Raman scattering (SERS) at a peak of 1612 cm(-1). After addition of human chorionic gonadotropin (hCG) an immune reaction with the ING probe occurred to form dispersive ING-hCG complexes with non-SERS activity that led to a decreased SERS peak at 1612 cm(-1). The decreased SERS intensity was linear to the concentration of hCG over 2.4-73.2 ng/mL. The ING reaction was studied in detail by SERS, scanning electron microscope (SEM), resonance Rayleigh scattering (RRS), surface plasmon resonance (SPR) absorption and laser scattering techniques. SERS quenching was observed and discussed.