A Ru-ZIF-8 nanozyme with both esterase like and peroxidase like activities were prepared for acetylcholine (ACh) detection. On the basis of the Ru-ZIF-8 nanozyme, a portable nanozyme strip was developed as a novel biosensor for detecting ACh, which was conducive to promoting the development of multiple enzyme cascade assays.

Abstract

In the present study, the incorporation of Ru into the framework of ZIF-8 resulted in that a Ru-ZIF-8 nanozyme with both esterase-like activity and peroxidase-like activity. Owing to the dual nanozymatic activities of Ru-ZIF-8 nanozyme, the acetylcholine (ACh) detection process utilized only one natural enzyme (choline oxidase), which greatly simplified the detection procedure. In the detection process, nanozyme Ru-ZIF-8 showed esterase-like activity to catalyze the hydrolysis of ACh to choline. Then the generated choline was oxidized by choline oxidase to generate H₂O₂. Finally, Ru-ZIF-8 with peroxidase-like activity was used to catalyze H₂O₂ to oxidize 2,2′-azino-bis (3-ethylbenzothiazo-line-6-sulfonic acid) ammonium salt with a color change. As a result, the linear range for ACh was from 0.01 μM-22 μM with the detection limit (DL) of 5.5 nM. In addition, Ru-ZIF-8 was utilized to fabricate a portable detection test strip. Our work provided a simple, portable, low-cost, highly sensitive and selective assay for the detection of ACh, which paved the way for the development of multi enzyme cascade assays.