Ultrasensitive nonenzymatic immunosensor based on bimetallic gold–silver nanoclusters synthesized by simple mortar grinding route

A simple nonenzymatic immunosensor was developed for sensitive and selective determination of squamous cell carcinoma antigen (SCC-Ag) based on bimetallic gold–silver nanoclusters (AuAg NCs) and reduced graphene oxide-tetraethylene pentamine (rGO-TEPA). rGO-TEPA was used as substrate material to immobilize antibodies since rGO-TEPA has large surface area and excellent conductivity to enhance the electrochemical response signal. AuAg NCs synthesized through simple mortar grinding route were used as catalytic labels of secondary antibodies; meanwhile, AuAg NCs could efficiently enhance the electron transfer. Under the optimal conditions, the electrochemical immunoassay exhibited a wide linear range of 0.005–20 ng/mL with a low detection limit of 1.3 pg/mL for SCC-Ag. The proposed sensing strategy enriches the electrochemical immunoassays and has a promising application in bioassay analysis.