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.

在此，基于聚酰亚胺/ CdS的Z方案复合物，成功设计了一种信号光电化学酶生物传感器，用于灵敏监测次黄嘌呤。黄嘌呤氧化酶（XOD）被集成到聚酰亚胺/ CdS复合物中以构建酶传感器。由于其独特的性能，聚酰亚胺（PI）不仅具有半导体分离和转移光生电子-空穴对的能力，而且还可以作为过氧化物模拟酶来催化H ₂ O ₂的还原，同时引入CdS。既有利于PI的光吸收，又可以及时传递PI产生的光生电子和空穴，以获得更稳定，更大的光电流信号。不像普通的O ₂依赖于信号的抑制，发现阴极光电流在一定范围内随衬底浓度的增加而变大。这种有趣的现象归因于由XOD和聚酰亚胺的协同作用形成的双重催化体系，并且阴极光电流的使用还避免了系统中还原性物质的干扰。所构建的酶生物传感器具有从10.0μM到10.0 mM的宽检测范围，并具有良好的分析性能，包括良好的选择性，灵敏度和高稳定性。