A dual-signal near-infrared fluorescent probe for concurrent detection of Hg²⁺ and ONOO⁻: Applications from environmental monitoring to imaging of Hg²⁺-induced oxidative stress.

As a highly toxic heavy metal, Hg²⁺ can accumulate in the human body through the food chain, causing multi-system damage, and induce the generation of peroxynitrite (ONOO⁻). The imbalance of ONOO⁻ is associated with various diseases, so it is necessary to accurately monitor both of them and the Hg²⁺-induced oxidative stress state in biological systems. Near-infrared (NIR) fluorescent probes are ideal tools, but most existing probes only detect Hg²⁺ or ONOO⁻ individually, and multifunctional probes are relatively scarce. In this study, a NIR fluorescent probe DCI-2a was developed. It uses dicyanoisophorone as the fluorophore and dimethyl thiophosphate as the recognition group. DCI-2a can react with Hg²⁺ to form an intermediate product, and react with ONOO⁻ to generate DCI-OH. During the response, it has large Stokes shifts (174 nm, 191 nm) to avoid background interference. Furthermore, this probe can not only be applied to the detection of Hg2 + in the environment, food, and plants, but also dynamically monitor Hg2+ and ONOO- in cells and zebrafish. Additionally, it has been utilized in acute mouse models of Hg²⁺ exposure to verify the induction of oxidative stress by Hg2+. DCI-2a has also preliminarily evaluated the efficacy of detoxification drugs for Hg²⁺ poisoning, providing experimental basis for analyzing the toxic mechanism of Hg²⁺ and developing related treatment and prevention strategies.