Rapid and accurate detection of carbosulfan residues in vegetables is important for ensuring food safety. Herein, based on the unique hydrolysis behavior of carbosulfan, a nanozyme-based colorimetric sensing platform was proposed for detection of carbosulfan. Hollow polydopamine/MnO2 nanoparticles (H-PDA/MnO2 NPs) with excellent oxidase-like activity were synthesized, which can promote the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) into blue oxidative product (oxTMB). Under acidic conditions, carbosulfan can be decomposed and produce reductive sulfide species (-SH), which are capable to disintegrate MnO2 NPs, resulting in decreased oxidase-like activity of H-PDA/MnO2 NPs. Based on the inhibitory effect on oxidase activity of H-PDA/MnO2 NPs, an acetylcholinesterase-free colorimetric assay was proposed for detection of carbosulfan with low limit of detection of 0.63ngmL-1. Integrating test swabs with smartphone, a portable colorimetric sensor was constructed, showing great potential for on-site detection. To demonstrate the feasibility of this method, carbosulfan in real vegetable samples were determined.
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