Bioinspired HOF nanozyme-enhanced hydrogel biosensor for smartphone-assisted detection of organophosphorus pesticide residues

Organophosphorus pesticides (OPs) have been increasingly used for agriculture production, but they have become a great threat to human health and environment due to their great hazard and difficult degradability. Thus, development of reliable and rapid detection methods for detection of OPs is of great importance. In this study, a smartphone-assisted hydrogel biosensor based on a hydrogen-bonded organic framework (HOF) nanozyme was developed for rapid and sensitive detection of OPs. Inspired by the catalytic active center of horseradish peroxidase (HRP), a novel HOF nanozyme with robust peroxidase (POD)-like catalytic activity was synthesized by combining HOF and Hemin, namely Hemin@HOF. The prepared Hemin@HOF nanozyme exhibited robust enzymatic activity, excellent storage stability, and high thermal stability. Benefiting from these merits, Hemin@HOF nanozyme was incorporated into hydrogel matrix to construct a HOF nanozyme-enhanced hydrogel biosensor for smartphone-assisted detection of OPs. By combining with acetylcholinesterase (AChE), the proposed HOF nanozyme-enhanced hydrogel biosensor can perform detection of OPs. By using this biosensor, chlorpyrifos was sensitively detected with a low limit of detection (LOD) (i.e., 3.04 ng/mL). Impressively, by coupling a smartphone, the hydrogel biosensor was greatly promising for rapid and on-site monitoring of OPs. This study not only developed a novel HOF nanozyme for smartphone-assisted OP sensing, but also provided a new insight for design of on-site detection methods of OPs.