Encapsulating acetylcholinesterase (AChE) into metal–organic frameworks for selective and sensitive colorimetric detection of carbaryl residue in water samples

This study presents the development of an AChE@ZIF-8 composite biosensor using a gold nanoparticle (AuNPs) probe as a naked-eye signal readout platform for the sensitive detection of carbamate pesticides. As a biomarker for carbaryl monitoring, we present the encapsulation of acetylcholinesterase within zeolitic imidazolate frameworks-8 (AChE@ZIF-8) to enhance its stability without losing its intended functions. In this research, synthesis work of AChE@ZIF-8 was carried out using a biomineralization approach and characterized by Powder X-ray Diffraction (PXRD), Fourier Transform Infrared (FTIR), Thermogravimetric analysis (TGA), and Brunauer–Emmett–Teller (BET). Computational modelling using Gaussian 16 was employed to provide qualitative electronic insight into the system. The encapsulation efficiency (EE%) of AChE within the ZIF-8 matrix was found to be 97.60%, which indicates highly effective enzyme loading and confirms the suitability of ZIF-8 as a robust carrier for enzyme immobilization. Acetylcholine (ACh) is catalysed by acetylcholinesterase to produce choline, which results in gold nanoparticles aggregating and a corresponding colour change. Under optimal conditions (temperature: 37 °C, buffer pH: 7.6, incubation time: 20 min, and ACh concentration: 4 mmol/L), the colour change can be employed for the detection of carbamate pesticides at low concentrations, with rapid sensitivity for carbaryl detection at a detection limit of 4.95 nM, and shows consistent performance in the analysis of spiked real water samples, achieving recoveries of 92.2–103.3%. AChE@ZIF-8 exhibits strong stability during biological storage, making it feasible for on-site carbaryl detection and showing great potential for wider applications in water pollutant monitoring.

Text 128103.pdf - Published Version Available under License Creative Commons Attribution Non-commercial No Derivatives. Download (1MB) Official URL or Download Paper: https://link.springer.com/10.1007/s00216-026-06729...

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