Porous organic polymers with donor-acceptor architectures as efficient photocatalytic oxidase-like nanozyme for colorimetric detection of organophosphorus pesticides.

Nanozymes, which are nanomaterials with enzyme-like activity, are commonly used for the detection of organophosphorus pesticides (OPs). However, most nanozyme-based sensors rely on peroxidase-like activity, which typically requires the use of hazardous and unstable hydrogen peroxide (H₂O₂), limiting their practical application. To overcome this limitation, we successfully prepared a photoactivated porous organic polymer (POP), Py-BDP, with a donor-acceptor structure. Its narrow bandgap and excellent charge transport properties enable efficient enzymatic catalytic activity under visible light, generating reactive oxygen species (ROS), such as •OH, O₂•⁻, and h⁺, which oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) to form blue ox-TMB. Furthermore, ox-TMB can be reduced to a colorless compound by thiocholine (TCh), which is created when acetylcholinesterase (AChE) reacts with acetylthiocholine (ATCh). Remarkably, OPs, being potent AChE inhibitors, prevented the generation of TCh. Based on the aforementioned approach, Py-BDP was cascaded with AChE to develop a colorimetric probe for OPs detection. It produced encouraging results in actual Chinese herbal medicine samples, with recoveries ranging from 86.73% to 100.31% and RSDs < 5%. As a result, this work might offer a wide range of opportunities for the advancement of visible, quick detection of OPs contamination, which is crucial for preserving food safety and environmental health.