Oxidase-like Nanozyme-Mediated Altering of the Aspect Ratio of Gold Nanorods for Breaking through H 2 O 2 -Supported Multicolor Colorimetric Assay: Application in the Detection of Acetylcholinesterase Activity and Its Inhibitors.

A convenient, fast, and colorful colorimetric platform with high resolution for acetylcholinesterase (AChE) activity and its inhibitors detection based on the regulation of oxidase-like nanozyme-mediated etching of gold nanorods (AuNRs) has been proposed in this work. MnO 2 nanosheets are selected as the nanozyme. Their excellent oxidase-like activity enables the etching process to proceed smoothly without the usage of unstable H 2 O 2 . When AChE is present, it catalytically hydrolyzes acetylthiocholine (ATCh) to thiocholine (TCh). With high reducing ability, TCh induces the decomposition of MnO 2 nanosheets, causing them to lose their oxidase-like activity. Thus, the etching of AuNRs is hampered. Consequently, with the increasing concentration of AChE, an apparent change in the AuNRs solution color is observed. The proposed platform achieves high-sensitivity detection of AChE (limit of detection = 0.18 mU/mL). Furthermore, the proposed platform also has been demonstrated its applicability for its inhibitors detection. Benefiting from the advantages of convenient and high resolution of visual readout, the proposed platform holds great potential for the detection of AChE and its inhibitors in clinical diagnosis.