Construction of an Activatable Near-Infrared Fluorescent Probe for Rapid Detection of Selenocysteine and Evaluation of Selenium-Supplementation Effect in Mouse Models

Abstract In this work, a robust activatable near-infrared (NIR) fluorescent probe (DCP-BS) was designed and synthesized for the highly selective and sensitive detection of selenocysteine (Sec). DCP-BS employs 2,1,3-benzoselenadiazole (BS) as the recognition moiety and utilizes Sec’s higher nucleophilicity compared to biothiols to achieve a specific response. The spectroscopic analysis indicated that the fluorescence is significantly enhanced upon reaction with Sec at 665 nm and reached a steady state within 65 s, with a limit of detection (LOD) as low as 71 nM. Selectivity experiments demonstrated that DCP-BS has an excellent selectivity for Sec over other various amino acids and biothiols. Impressively, fluorescence-living image results in the selenium-supplemented mouse model, showing DCP-BS successfully visualized the dynamic changes of the Sec levels in vivo. In addition, the DCP-BS can quantitatively detect Sec levels in mouse blood while being virtually unaffected by matrix-induced fluorescence quenching or enhancement in complex food matrices, and it yields good recovery rates. Therefore, this work provided a unique methodological reference for evaluating selenium nutrition in food and monitoring selenium metabolism in biosystems.