Construction of photocathodic bioanalytical platform based on Z-scheme polyimide/CdS composite assisted by dual-catalysis system

Abstract

Herein a signal-on photoelectrochemical enzyme biosensor is successfully designed for sensitive monitoring of hypoxanthine based on the Z-scheme composite of polyimide/CdS. Xanthine oxidase (XOD) is integrated into the polyimide/CdS composite to construct an enzyme sensor. Due to its unique properties, polyimide (PI) not only has the ability of semiconductor to separate and transfer photogenerated electron-hole pairs, but also acts as a peroxide mimic enzyme to catalyze the reduction of H2O2, while the introduction of CdS is conducive to the light absorption of PI, and can also transfer the photogenerated electrons and holes generated by PI in time to obtain a more stable and larger photocurrent signal. Unlike the common O2-dependent suppression of the signal, it is found that the cathode photocurrent becomes larger with the increase of the substrate concentration in a certain range. This interesting phenomenon is ascribed to the dual-catalysis system formed by the synergistic action of XOD and polyimide, and the use of cathode photocurrent also avoids the interference from reducing substances in the system. The constructed enzyme biosensor has a wide detection range from 10.0 μM to 10.0 mM and exhibits favorable analytical performance including good selectivity, sensitivity and high stability.