Nanogold/graphene as sensing platform coupled with ferrocene/gold as signal amplifier for sandwich-like voltammetric immunosensor of human chorionic gonadotropin.

An effective method to detect human chorionic gonadotropin (hCG) is of significance for early pregnancy testing and clinical diagnosis of non-pregnancy related diseases. Herein, a sensitive sandwich-like electrochemical immunosensor of hCG was constructed by introducing nanogold/graphene (Au/GNS) hybrids and ferrocene/gold nanoparticles (Fc/Au) as the sensing platform and signal amplifier, respectively. In this sensing platform, the Au/GNS hybrid was dedicated to increasing the loading capacity of primary antibody (Ab1) and accelerate the electron transport, and Au is devoted to assembling secondary antibodies (Ab2) and Fc derivative (Fc-SH) to fabricate signal amplifier (Ab2-AuNPs-Fc). By selecting Fc as the signal probe, results revealed that peak currents increased when the special recognition among Ab1, hCG, and Ab2 occurred. A novel and sensitive sandwich-like immunosensor of hCG was thus constructed. After optimizing various testing conditions, a wide linearity from 0.005 to 7.0 ng mL-1 and a low detection limit of 1.0 pg mL-1 were achieved for hCG analysis, suggesting this method is useful for hCG analysis. AJTR