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

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@C 60 -Polyamidoamine (Au@C 60 -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 H 2 O 2 , which could act as the coreactant of PFO to enhance the ECL intensity. Due to the excellent ECL property of PFO–H 2 O 2 system, our prepared biosensor showed a wide linear range from 0.001   ng/mL to 10   ng/mL, and a low detection limit down to 0.0003   ng/mL. The integration of excellent ECL property of PFO–H 2 O 2 system and excellent catalytic activity of Au@C 60 -PAMAM would open a new and promising platform for fabricating ECL biosensors and biocatalysts.