In Situ Biomineralization and Citric Acid Etching\nStrategy for Enhancing Activity of Immobilized Acetylcholinesterase

Enhancing\nthe structural stability of an enzyme and maintaining\nits catalytic activity are effective ways to improve enzyme utilization\nand reduce the cost of drug screening. However, immobilized enzyme\nactivity tends to decrease in existing immobilization techniques due\nto conformational changes and microenvironmental restrictions. In\nthis paper, we present a facile approach to prepare immobilized acetylcholinesterase\n(AChE) with high activity by a ZIF-8 in situ immobilization and citric\nacid (CA) etching strategy. CA breaks the coordination bond of ZIF-8\nand produces defects, expanding the pore space, improving substrate\naccessibility, and fully exposing the active site of the enzyme. The\nenhancement of the catalytic activity of AChE@ZIF-8-CA was about 6.10-fold\ncompared with the free enzyme. In addition, AChE@ZIF-8-CA exhibited\nan excellent encapsulation efficiency and good tolerance to temperature,\npH, and organic solvents. The relative activity remains at the initial\n83.77% even in five repeated experiments. The strategy provides a\nnovel and efficient way to quickly construct highly active immobilized\nenzymes under mild conditions.