Measurement of acetylcholinesterase activity by electrochemical analysis method utilizing organocatalytic reactions

Abstract

An electrochemical method for measuring acetylcholinesterase (AChE) activity was developed using nortropine-N-oxyl (NNO), an organocatalyst. The increase in catalytic current as NNO oxidizes choline allowed real-time monitoring of the AChE hydrolysis reaction. Compared to conventional H₂O₂-based sensors, this method eliminates one reaction step, enabling more direct and real-time monitoring of enzymatic activity. Amperometric measurements enable AChE activity determination over a range of 50–2000 U L⁻¹ and the limit of detection and limit of quantification in the low concentration range were calculated to be 14.1 U L⁻¹ and 46.9 U L⁻¹, respectively, with a correlation coefficient (R²) of 0.9989. These results demonstrate that serum cholinesterase measurement using this method can be utilized for various diagnoses, such as liver and heart diseases. Furthermore, given the relevance of AChE in neurotoxicity evaluation, diagnosis of neurological disorders such as Alzheimer's disease, and environmental toxicity monitoring, this method has diverse potential applications. Moreover, this approach can be extended to other enzymatic reactions, indicating its promise for various analytical and diagnostic applications.