Mechanism and optimization of a Hg2+-triggered nanozyme based on chitosan-carbon quantum dots-tellurium nanoparticles

Chitosan-carbon quantum dots-tellurium nanoparticles (CS-CQDs-TeNPs) was a multifunctional nanozyme integrating high stability, photoluminescence, and enzyme-like catalytic activity. • Hg 2+ specifically triggered the oxidase-like activity of CS-CQDs-TeNPs through a ping-pong mechanism. • The mechanism proceeded via in-situ formation of HgTe, which catalyzed ROS (O 2 - /·OH) generation to oxidize the substrate for colorimetric detection. • The CS-CQDs-TeNPs-based colorimetric sensor demonstrated high selectivity and strong anti-interference capability, enabling reliable detection of Hg 2+ in environmental water samples. • The sensor performed on-site detection and simultaneous detoxification of Hg 2 (via conversion to HgTe), presenting a dual-function platform for mercury pollution control. Herein, a CS-CQDs-TeNPs-based colorimetric sensor was developed for the highly sensitive detection and simultaneous harmless conversion of Hg 2+ . In the presence of Hg 2+ , the oxidase-like activity of CS-CQDs-TeNPs was specifically triggered, and its catalytic kinetics followed the ping-pong mechanism. Under conditions of pH 4.0 and 30 °C, the colorimetric sensor constructed from 38.6 μg/mL CS-CQDs-TeNPs and 1.040 mmol/L TMB exhibited optimal activity, demonstrating a V max of 83 (10 −8 ·M·s −1 ) and a K m of 13 mmol/L. Mechanistic studies indicated that Hg 2+ reacted with CS-CQDs-TeNPs to form HgTe in situ. The generated HgTe catalyzed the generation of reactive oxygen species from O 2 . These reactive oxygen species, in combination with the surface oxygen vacancies of the CS-CQDs-TeNPs, synergistically oxidized TMB, thus resulting in a colorimetric response. The CS-CQDs-TeNPs-based colorimetric sensor exhibited excellent selectivity, anti-interference capability, and considerable detection potential, while converting Hg 2+ into low-toxicity HgTe during detection, thus realizing the integration of detection and remediation. This study provides a novel strategy for designing environmentally responsive nanozymes and remediating Hg 2+ pollution.