Resonance Scattering Spectral Determination of Trace Penicillin G Using Immunonanogold‐HAuCl₄‐NH₂OH Catalytic Reaction

Abstract

Both nanogold and immunonanogold exhibit catalytic effect on the slow reaction of HAuCl 4 -NH 2 OH to form gold particles which displayed a resonance scattering (RS) peak at 580 nm. Using hapten penicillin G (PG) as a model, the nanogold in size of 9 nm was used to label rabbit anti-penicillin G antisera (RAPG) to obtain an immunonanogold probe (AuRAPG) for PG. The PG was combined with AuRAPG to form the immunocomplex and bigger nanogold clusters. After centrifugation, the excess AuRAPG in the supernatant exhibited catalytic effect on the reaction of HAuCl 4 -NH 2 OH, and the RS intensity at 580 nm (I 580 nm ) was enhanced greatly. With the addition of PG, the I 580 nm decreased accordingly. Under the optimal conditions, the decreased intensity ΔI 580 nm was proportional to the PG concentration in the range of 0.15-225 ng/mL, with a detection limit of 0.05 ng/mL for PG.