Capacitive monitoring of the antigen-antibody reactions enhanced by nanogold

An immunosensor for measuring antigen-antibody binding by nanogold particles enhancement was presented here. A gold plate electrode was modified by a SAM (self-assembled monolayer) of 11-mercaptoundecanioc acid. Then sheep anti-rabbit IgG was immobilized onto the end of the 11-mercaptoundecanioc acid. With that the gold electrode was exposed to the mixed solution of rabbit IgG and nanogold labeled sheep anti-rabbit IgG. The differential capacitance of the electrical double layer was monitored to detect the antigen-antibody reaction. The result showed the capacity of the electrical double layer by nanogold enhancement was largely increased compared to that in traditional capacitive immunosensor. The detection sensitivity is up to 10nF/mug/ml