Photoelectrochemical biosensor for acetylcholinesterase activity study based on metal oxide semiconductor nanocomposites

Acetylcholinesterase (AChE) is a well-known serine hydrolase and its dysfunction could disturb cholinergic neurotransmission which is related to the pathogenesis of neurodegenerative disorders. In this report, a photoelectrochemical biosensor based on metal oxide semiconductor nanocomposite was fabricated to investigate the effect of cadmium ion (Cd^2 +) on the activity of AChE. The photoelectrochemical nanocomposite was prepared by anodic oxidation of titanium (Ti) foil to form titanium dioxide (TiO₂) nanotubes (TNs) array followed by cathodic deposition of zinc oxide nanorods (ZnONRs) onto the TNs. AChE was immobilized on the obtained nanocomposites and the biosensor showed enhanced photoelectrochemical response under visible light irradiation. The experimental results showed that Cd^2 + exhibited interesting dose-dependent and time-dependent effects on AChE activity. Specifically, high concentration of Cd^2 + inhibited while low level of Cd^2 + could stimulate the activity of AChE. These findings are of great significance for the study of enzyme activity influenced by metal ions and related pathogenesis investigation of neurodegenerative disorders.