Degradable photoactivated metal–organic frameworks with oxidase-like nanozyme for the colorimetric detection of galantamine

Abstract

Monitoring the acetylcholinesterase (AChE) activity is crucial yet challenging for the early diagnosis and therapeutic monitoring of neurological disorders. In this study, a novel colorimetric sensing platform for detecting the AChE inhibitors was developed by integrating the light-responsive oxidase-mimicking activity of ZIF-90 with the catalytic hydrolysis mediated by AChE. ZIF-90, a stimuli-responsive nanomaterial, retained its pH-dependent dissolution behavior and underwent disintegration under acidic conditions. Leveraging this intelligent responsiveness, ZIF-90 oxidized colorless TMB to blue oxTMB under visible-light irradiation at neutral pH without requiring H₂O₂, exhibiting a strong characteristic absorption peak at 652 nm for oxTMB. Critically, acetic acid generated during the AChE-catalyzed hydrolysis reaction induced the decomposition of ZIF-90, thereby yielding a weakened colorimetric signal. In the presence of galantamine hydrobromide (GH), GH bound to AChE and inhibited its enzymatic activity. Consequently, ZIF-90 disintegration was suppressed, allowing the sustained catalytic oxidation of TMB and resulting in an intensified absorbance signal. The resulting colorimetric sensing platform exhibited a broad linear detection range and achieved a low detection limit of 3.15 pM. Moreover, this strategy was readily adaptable to other AChE inhibitors and performed well in real samples.