Colorimetric Assay for Acetylcholinesterase Activity and Inhibitor Screening Based on Metal–Organic Framework Nanosheets

-initiated oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) to blue oxidized TMB (ox-TMB). Such catalytic performance inspired us to develop a convenient, rapid, and sensitive acetylcholinesterase activity assay, during which AChE can catalyze the substrate acetylthiocholine (ATCh) to produce thiocholine (TCh), and TCh could especially enable the degradation of 2D Zn-TCPP(Fe) NSs accompanied by the reduction of ox-TMB production. Our proposed sensing system exhibited favorable selectivity and sensitivity (LOD of 0.029 mU/mL) and has excellent potential to evaluate AChE activity in human serum samples and to screen AChE inhibitors. This colorimetric assay could provide an alternative pathway for early diagnosis and drug screening of AD, facilitating the development of AD therapy.