Visual evaluation of acetylcholinesterase inhibition by an easy-to-operate assay based on N-doped carbon nanozyme with high stability and oxidase-like activity

Acetylcholinesterase (AChE) is the key enzyme associated with neurotransmission, and thus many drugs have been explored for their inhibitory effect on AChE, such as donepezil for Alzheimer's disease and organophosphorus pesticides (OPs). Compared with clinical trials, in vitro screening bioassays for AChE inhibitors are preferable in terms of operability and cost. Herein, we developed an easy-to-operate nanozyme-based colorimetric assay for the evaluation of AChE inhibitory strength with excellent anti-interference ability and low dependence on professional equipment. The metal-free carbon nanozyme NC900 played an important role in the signal output due to its features of efficient oxidase-like activity, excellent water dispersibility, high stability and low color interference. Employing various AChE-targeted or non-targeted pesticides as examples, the as-proposed assay exhibited excellent distinguishing ability for different chemicals. The higher absorption intensity at 652 nm represents a stronger inhibitory effect, as well as blue color. In addition, this method was used to study the influence of pH on the degradation of prodrugs, and the efficiency of mixed pesticides. This work provides a simple and reliable assay to screen AChE inhibitors, which is promising for the preliminary evaluation of a large number of potential candidates.