Synthesis of colloidal gold using high-molecular-weight reducing agents

High-molecular-weight reagents, polyethylenimine, polyethylene glycol, and polyvinylpyrrolidone, were used to prepare colloidal gold by reducing chlor oauric acid. The data on the kinetics of the reduction process were obtaine d by the spectrophotometric method in the near ultraviolet, visible, and ne ar infrared regions. Substantial differences in the kinetics of the reducti on of chloroauric acid when using low- (sodium citrate) and high-molecular- weight reducing agents were noted. The single-stage procedure for the prepa ration of the biospecific marker-conjugate of colloidal gold with immunoglo bulin - was developed using a protein and a low-molecular-weight reducing a gent (sodium borohydride) in the reduction of chloroauric acid. Possible sp ecific features of the synthesis mechanism of chloroauric acid were discuss ed in the case of using high-molecular-weight reagents as reducing agents.