Highly sensitive colorimetric detection of arsenite based on reassembly-induced oxidase-mimicking activity inhibition of dithiothreitol-capped Pd nanozyme

Given that hypertoxic arsenite (As3+) poses a serious threat to the environment and global health, developing high-performance, low-cost and easy-to-use approaches to specifically monitor As3+ in environmental matrices turns to be of great importance. In the present work, we reported a novel colorimetric assay of As3+ based on the reassembly-induced oxidase-like activity inhibition of dithiothreitol-capped Pd nanoparticles (Pd-DTT). The Pd-DTT nanozyme exhibits good oxidase-like catalytic activity to trigger the oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of O-2, forming a blue product TMBox. When As3+ exists, it can chelate the sulfydryl groups in DTT more strongly, leading to a reassembly of Pd-DTT. Compared with the original nanozyme, the reassembled one has much less oxidase-like activity, resulting in the significantly suppressed TMB reaction. Based on this principle, highly sensitive detection of As s+ was achieved, providing a wide linear range from 33 ng(-1) to 333.3 mu g L-1 and an ultralow detection limit of 35 ng(-1). With the help of EDTA as a chelating agent, the method could also offer excellent selectivity for the determination of As3+ against other metal ions. Besides, our colorimetric assay was employed to accurately measure the analyze in spiked drinking and river water, revealing its great promise in environmental analysis application.