An ultrasensitive electrochemiluminescent biosensor for the detection of concanavalin A based on poly(ethylenimine) reduced graphene oxide and hollow gold nanoparticles.

A highly sensitive electrochemiluminescent (ECL) biosensor was designed for the detection of concanavalin A (ConA) based on glucose oxidase (GOx) as a recognition element by carbohydrate-lectin biospecific interaction, and poly(ethylenimine) (PEI) reduced graphene and hollow gold nanoparticles (HAuNPs) as supporting matrix and signal amplifier. The modification process and detection principle of the biosensor are briefly described as follows. First, PEI reduced graphene oxide with abundant amino groups was cast onto the surface of glassy carbon electrode to adsorb HAuNPs for improving the signal intensity in luminol/H2O2 ECL system. Next, GOx was further assembled onto the electrode by the interaction between Au and -NH2. In the presence of glucose in the detection solution, GOx catalyzed glucose to generate H2O2 in situ, which served as a co-reactant of luminol to enhance ECL signal of luminol. Based on the fact that ConA could result in a decrease in ECL signal when immobilized on the electrode, an ECL biosensor was prepared for the determination of ConA. The ECL signal intensity was linear with the logarithm of ConA concentration and the linear range was from 1.0 to 20 ng/mL with a low detection limit of 0.31 ng/mL (signal to noise ratio =3). This strategy led to a nearly 1000-fold improvement in detection limit for ConA assays compared with previously reported method, thus exhibiting a great potential application in sensitive bioassays of ConA.