A sandwich electrochemiluminescent biosensor based on enzymatic reaction to in situ generate coreactant of conjugated polymer for Con A detection

Abstract

A novel “signal-on” biosensor for the detection of concanavalin A (Con A) was designed utilizing an enzymatic reaction to in situ generate coreactant of poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO). Firstly, PFO polymers were wrapped with graphene oxide nanosheets to obtain GO@PFO nanocomposite, which was modified onto the surface of the electrode as a matrix for immobilizing phenoxy-derivatized dextran (Dexp) through π-π stacking interaction. Then Con A interacted with Dexp through the specific carbohydrate-protein interaction. Finally, glucose oxidase (GOx) and lactate oxidase (LOx) decorated gold nanoparticles@C60-Polyamidoamine (Au@C60-PAMAM) was bound onto Con A via a biospecific interaction between Con A and the internal residues of GOx, thus achieving a sandwich structure. In this construction strategy, LOx catalyzed the oxidation of lactate to in situ generate H2O2, which could act as the coreactant of PFO to enhance the ECL intensity. Due to the excellent ECL property of PFO–H2O2 system, our prepared biosensor showed a wide linear range from 0.001ng/mL to 10ng/mL, and a low detection limit down to 0.0003ng/mL. The integration of excellent ECL property of PFO–H2O2 system and excellent catalytic activity of Au@C60-PAMAM would open a new and promising platform for fabricating ECL biosensors and biocatalysts.