An enzyme-free photoelectrochemical sensing of concanavalin A based on graphene-supported TiO2 mesocrystal

This work designed a delicate signal-on photoelectrochemical sensing methodology for concanavalin A monitoring by coupling graphene-supported quasi-octahedral TiO2 mesocrystal with an efficient enzyme-free labeling strategy. Herein, graphene with prominent conductivity could accelerate photo-generated electrons transfer, thus enhancing the photocurrent response. Currently, labeling of various enzymes was the mainly strategy for signal amplification, unfavorably, this method usually suffered inferior stability. Hence, the exploration and development of NiCo2O4 labeling was proposed here, which could effectively accept the photo-induced electrons from conduction band of TiO2 mesocrystal, leading to the decrease of the photocurrent intensity. Accordingly, a signal-on non-enzymatic photoelectrochemical sensor was constructed based on immobilized concanavalin A competing with isolated concanavalin A of various concentrations for reaction with the NiCo2O4 labeled glucose conjugates. Under the optimized conditions, the photocurrent increased with the increasing concanavalin A concentration in a dynamic linear range from 0.05 ng/mL to 0.5 μg/mL, thereby proposing a general format for practical use in quantitative determination of concanavalin A. Promisingly, the successful consideration of graphene sensitized TiO2 mesocrystal further broadened the application of excellent photoactive materials for photoelectrochemical sensing platform.