Peroxide-like enzymes with fluorescent properties for colorimetric/fluorescent dual-mode detection and degradation of organophosphorus pesticide.

Abstract

Organophosphorus pesticides (OPs) are widely used in modern agriculture to ensure crop yields; however, their high chemical stability and environmental persistence pose significant risks to human health and ecosystems through food chain bioaccumulation. Traditional detection methods, such as chromatography and immunoassays, are often limited by high instrumental costs, complex sample pretreatment, and lengthy procedures, while conventional degradation strategies suffer from poor selectivity and harsh reaction conditions. Herein, we report a bifunctional nanozyme system that integrates polyvinylpyrrolidone-modified copper nanoclusters (PVP-CuNCs) with MnO2 nanosheets to achieve simultaneous dual-mode detection and catalytic degradation of OPs. The fluorescence mode exploits the acetylcholinesterase (AChE) inhibition mechanism, in the presence of OPs, thiocholine (TCh) production is suppressed, preserving the MnO2-mediated fluorescence quenching of PVP-CuNCs, whereas in OPs-free conditions, TCh reduces MnO2 to Mn2+, leading to fluorescence recovery. Concurrently, the colourimetric mode utilises the intrinsic peroxidase-like activity of the composite to catalyse the oxidation of 3, 3', 5, 5'-tetramethylbenzidine (TMB), enabling rapid visual readout. This dual-mode approach offers complementary signal validation, achieving detection limits as low as 0.06 nM (fluorescence) and 1.3 nM (colorimetry) across a broad linear range. Furthermore, the PVP-CuNCs@MnO2 composite efficiently activates peroxymonosulfate (PMS) to generate reactive oxygen species, enabling approximately 99.8% degradation of OPs within 12 min under ambient conditions. By bridging on-site detection with rapid catalytic remediation in a single platform, this integrated system provides a cost-effective, efficient, and sustainable solution for ensuring food safety and environmental remediation.