Preparation of a Red-Emitting, Chitosan-Stabilized Copper Nanocluster Composite and Its Application as a Hydrogen Peroxide Detection Probe in the Analysis of Water Samples.

Hydrogen peroxide (HO) is an important reactive oxygen species that mediates a variety of physiological functions in biological processes, and it is an essential mediator in food, pharmaceutical, and environmental analysis. However, HO can be dangerous and toxic at certain concentrations. It is crucial to detect the concentration of HO in the environment for human health and environmental protection. Herein, we prepared the red-emitting copper nanoclusters (Cu NCs) by a one-step method, with lipoic acid (LA) and sodium borohydride as protective ligands and reducing agents, respectively, moreover, adding chitosan (CS) to wrap LA-Cu NCs. The as-prepared LA-Cu NCs@CS have stronger fluorescence than LA-Cu NCs. We found that the presence of HO causes the fluorescence of LA-Cu NCs@CS to be strongly quenched. Based on this, a fluorescent probe based on LA-Cu NCs@CS was constructed for the detection of HO with a limit of detection of 47 nM. The results from this research not only illustrate that the as--developed fluorescent probe exhibits good selectivity and high sensitivity to HO in environmental water samples but also propose a novel strategy to prepare red-emitting copper nanoclusters (Cu NCs) by a one-step method.