Abstract
This paper presents a potentiometric enzyme biosensor for acetylcholine based on a zinc oxide (ZnO) thin film. The sensing film is modified with acetylcholinesterase (AChE) and choline oxidase (ChOx) to enhance sensing performance. Furthermore, the sensing film utilizes the surface chemistry of metal oxides, functionalizing the ZnO thin film with (3-aminopropyl) triethoxysilane (APTES). AChE-ChOx is then immobilized on the working electrode via glutaraldehyde (GA) cross-linking. Potentiometric measurements using the time-voltage (V-T) method demonstrate a linear detection range of 10 nM to $100~\upmu $ M, with a detection limit as low as 6.33 nM, reaching physiological concentrations. This sensor exhibits an average sensitivity of 48.20 mV/decade, a linearity of 0.990, a response time of 17 seconds, and excellent anti-interference performance.