A sandwich-like electrochemiluminescent biosensor for the detection of concanavalin A based on a C-60-reduced graphene oxide nanocomposite and glucose oxidase functionalized hollow gold nanospheres

A sensitive sandwich-like electrochemiluminescent (ECL) biosensor was designed for the detection of concanavalin A (ConA) using a C-60-reduced graphene oxide (C-60-rGO) nanocomposite as a platform and glucose oxidase (GOX) decorated hollow gold nanospheres (HGNSs) as a label. First, C-60-rGO with a large surface area was prepared for combining with phenoxy-derivatized dextran, which served as the recognition element for interacting with ConA by biospecific carbohydrate-protein (lectin) interactions. Then, GOX decorated HGNSs (GOX-HGNSs) were linked to the electrode surface through the biospecific interaction between the intrinsic carbohydrate residues of GOX and ConA. These localized GOX and HGNSs amplified the ECL signal of luminol intensely, which was achieved by the efficient catalysis of the GOX towards the oxidation of glucose to in situ generate an improved amount of hydrogen peroxide (H2O2) as a coreactant, and the excellent catalysis of HGNSs towards the ECL reaction of luminol-H2O2. The prepared biosensor exhibited a sensitive response for the determination of ConA, ranging from 0.10 to 100 ng mL(-1) with a detection limit down to 30 pg mL(-1) (signal to noise = 3). With excellent stability, sensitivity, selectivity and simplicity, the prepared biosensor showed great prospects in lectin sensing or carbohydrate sensing.