Quenched solid-state electrochemiluminescence of gold nanoclusters and the application in the ultrasensitive detection of concanavalin A

This work investigated the quenching effect of ferrocenecarboxylic acid (Fc-COOH) on the bovine serum albumin-stabilized Au nanoclusters-triethylamine (Au 25 -Et 3 N) electrochemiluminescence (ECL) system. Based on the annihilation between the oxidation product of Fc (Fc + ) and Et 3 N radical, a quenching-based sandwich-configuration ECL biosensor was established for sensitive and specific detection of concanavalin A (ConA). Au 25 with strong initial ECL signal were modified onto the glassy carbon electrode (GCE) for immobilizing glucose oxidase (GOD). With the further immobilization of target ConA, the quenching probe of GOD@Fc-COOH-PtPd nanocubes were incubated onto the electrode through a specific carbohydrate-ConA interaction, thus achieving a sandwich structure. The resulting ECL biosensor showed a wide linear range from 0.004   ng/mL to 90   ng/mL and a low detection limit of 0.001   ng/mL (S/N   =   3) for ConA detection. The integration of Fc-COOH with Au 25 -Et 3 N system would hold a great promise in bioanalysis.