Zirconium and vanadium bimetallic organic framework nanozyme for bioenzyme-free colorimetric and photothermal dual-mode direct detection of organophosphorus pesticides

Abstract

Presently, the majority of colorimetric methods for the detection of organophosphorus pesticides (OPs) generally require the presence of bioenzymes coupled with just single-signal detection mode. Herein, using VCl₃ and ZrCl₄ as the metal precursors and 2-aminoterephthalic acid as the coordination ligand, we successfully designed and prepared a novel bimetallic Zr/V-based UiO-66-NH₂ organic framework nanozyme for the first time, which could offer prominent peroxidase (POD)-like activity to efficiently catalyze the oxidation of 3,3,5,5-tetramethylbenzidine. Results revealed that this oxidation process could induce a color change in the nanozyme catalytical system, and interestingly, the system temperature increased after the use of a near infrared laser. Additionally, the as-prepared bimetallic nanozyme could specifically bond with the OP structure, inhibiting its POD-like activity. Based on these interesting phenomena, a bioenzyme-free colorimetric-photothermal dual-mode direct sensing strategy of OPs was proposed for the first time. Upon optimizing various conditions, the as-proposed sensing strategy achieved simple, sensitive and direct dual-mode detection of OPs, offering a new method for OP analysis in real applications.