Acetylcholinesterase Activity Monitoring and Natural Anti-neurological Disease Drug Screening via Rational Design of Deep Eutectic Solvents and CeO2-Co(OH)2 Nanosheets

The activity monitoring of acetylcholinesterase (AChE) and the screening of its inhibitors are critical for the diagnosis and therapy of neurological diseases. Herein, CeO₂-Co(OH)₂ nanosheets were synthesized for the first time in a newly designed deep eutectic solvent (DES) composed of l-proline and Ce(NO₃)₃·6H₂O, and a colorimetric assay was developed for quantitative detection of AChE and anti-neurological disease drug screening. Impressively, CeO₂-Co(OH)₂ composites prepared in DESs have more prominent oxidase-like activity than Co(OH)₂, CeO₂, and CeO₂-Co(OH)₂ produced in aqueous solution. The mechanism study shows that the oxygen vacancies of CeO₂-Co(OH)₂ play a vital role in oxidase-like catalysis. Based on their excellent oxidase-like activity, the CeO₂-Co(OH)₂ nanosheets have been successfully applied for highly sensitive and selective detection of AChE with a linear range of 0.2-20 mU/mL. This strategy can also be used for inhibitor screening. The sensor displays an excellent linear response in the range of 0.001-2 μg/mL toward an irreversible inhibitor (paraoxon-ethyl). Moreover, five alkaloids, namely, berberine hydrochloride, caffeine, camptothecin, matrine, and evodiamine, were screened by using neostigmine bromide as a control; berberine hydrochloride exhibited a good inhibitory effect on AChE with an IC₅₀ of 0.94 μM, while the other four had no obvious inhibitory effect. The mechanism of the different effects of alkaloids on inhibiting acetylcholinesterase activity was explored via molecular docking and kinetic simulation.