Photoelectrochemical platform for glucose sensing based on g-C3N4/ZnIn2S4 composites coupled with bi-enzyme cascade catalytic in-situ precipitation

A unique bi-enzyme photoelectrochemical (PEC) biosensor is developed for selective and sensitive detection of glucose based on bi-enzyme cascade catalytic in-situ precipitation for signal amplification. In this design, the composites of ZnIn2S4 and graphitic carbon nitride (g-C3N4/ZnIn2S4) with better photoelectrochemical properties are used as the photoactive material. Subsequently, horseradish peroxidase (HRP) and glucose oxidase (GOx) are anchored on the modified electrode surface. In the presence of 4-chloro-1-naphthol (4-CN) and glucose, GOx catalyzes the oxidation of glucose to produce H2O2 , which oxidizes 4-CN to generate a precipitate in the presence of HRP. The precipitate on the electrode surface can dramatically reduce the photocurrent signal. In the light of the signal magnification process, the bi-enzyme biosensor presents a signal-off sensing mode for glucose detection, which displays a dynamic detection range of 1-10000 mu M with a low limit of detection of 0.28 mu M. Furthermore, the constructed PEC bi-enzyme biosensor exhibits a tremendous potential for quantitative detection of glucose in practical applications.