Pt-VS2-MXene nanozyme for on-site pesticide and H2O2 sensing: Bridging computational insights and experiment

Abstract

The excessive use of chlorpyrifos (CPS), a widely applied organophosphate pesticide, has caused serious environmental and food contamination, necessitating rapid and selective detection. Likewise, sensitive detection of H<inf>2</inf>O<inf>2</inf> in living cells is crucial given its role in reactive oxygen species-mediated signalling, cell growth, and apoptosis. In this study, we synthesized peroxidase-mimetic nanozyme, Pt nanoparticles on edge-defect V<inf>2</inf>C MXene decorated with VS<inf>2</inf> (VS<inf>2</inf>–MXene) via chemical reduction and solvothermal processes for ultrasensitive CPS and H<inf>2</inf>O<inf>2</inf> detection. The defect-engineered Pt–VS<inf>2</inf>–MXene nanozyme exhibits markedly enhanced peroxidase-like activity (90.6 U mg−1), exceeding Pt–VS<inf>2</inf> (40.5 U mg−1), Pt–MXene (64.9 U mg−1), and VS<inf>2</inf>–MXene (26.8 U mg−1), and substantially outperforming conventional nanozymes. Taking into account the ability of CPS to inhibit the peroxidase-like activity of Pt–VS<inf>2</inf>–MXene and suppressing its catalytic oxidation of chromogenic 3,3′,5,5′-tetramethylbenzidine (TMB), we constructed a smartphone-integrated paper-based analytical device (PAD) for real-time CPS detection. The PAD sensor enables ultrafast (∼3 min), visual, and on-site CPS quantification, achieving a detection limit of 0.64 nM with a broad linear range of 10–140 nM, and excellent recovery of 105.2 %–108.2 % in real wastewater samples. Additionally, Pt–VS<inf>2</inf>–MXene exhibits exceptional catalytic activity, with a strong affinity for TMB (Kₘ = 0.0231 mM, Vₘₐₓ = 0.169 µM s⁻1), enabling ultra-sensitive H<inf>2</inf>O<inf>2</inf> detection (LOD = 0.08 nM) with the wide linear range of 10–900 nM and real-time monitoring of H<inf>2</inf>O<inf>2</inf> secretion from HeLa cells. This work creates sensitive PADs that can be used in biosensing, environmental monitoring, and medical diagnostics. © 2025 Elsevier B.V., All rights reserved.