Metal-organic framework-based multienzyme cascade bioreactor for sensitive detection of methyl parathion.

Scheme 1. Schematic diagram of ZIF-8-based cascade amplification nanobioreactor for the detection of MP in fruits and vegetables. [Display omitted] • A cascaded scale-up nanobioreactor based on ZIF-8 was designed. • AChE/CHO@ZIF-8 was a target identification and signal amplification unit. • This ZIF-8-based nanoreactor improves the catalytic efficiency of cascade enzymes. • Dual-emission GSH-AuNCs have excellent luminescence due to ZIF-8 constraining. • The biosensor successfully achieved the detection of MP in fruits and vegetables. In this study, a cascade nanobioreactor was developed for the highly sensitive detection of methyl parathion (MP) in food samples. The simultaneous encapsulation of acetylcholinesterase (AChE) and choline oxidase (CHO) in a zeolitic imidazole ester backbone (ZIF-8) effectively improved the stability and cascade catalytic efficiency of the enzymes. In addition, glutathione-stabilized gold nanoclusters (GSH-AuNCs) were encapsulated in ZIF-8 by ligand self-assembly, conferring excellent fluorescence properties. Acetylcholine (ATCh) is catalyzed by a cascade of AChE/CHO@ZIF-8 as well as Fe(II) to generate hydroxyl radicals (·OH) with strong oxidizing properties. The ·OH radicals then oxidize Au(0) in GSH-AuNCs@ZIF-8 to Au(I), resulting in fluorescence quenching. MP, as an inhibitor of AChE, hinders the cascade reaction and thus restores the fluorescence emission, enabling its quantitative detection. The limit of detection of the constructed nanobioreactor for MP was 0.23 µg/L. This MOF-based cascade nanobioreactor has great potential for the detection of trace hazards. [ABSTRACT FROM AUTHOR]