Robust Fluorescent\nNanoprobe for Rapid Evaluation\nof the Selenium Supplementation Effect and Imaging

At present, an increasing number of people pay more attention\nto\nselenium-enriched food, but the quality of the selenium-enriched food\nvaries. Therefore, there is an urgent need to develop a new tool to\nassess the effects of selenium supplementation in foods by rapidly\ndetecting the levels of the metabolite selenium selenocysteine (Sec).\nIn this work, a fluorescent nanoprobe <b>CS-Sec</b> was designed,\nsynthesized, and characterized for Sec detection and imaging in living\nbiosystems, which exhibited the advantages of good biocompatibility,\nexcellent water solubility, high sensitivity, high selectivity, and\nrapid response (2.5 min) for Sec detection and imaging <i>in\nvitro</i> and <i>in vivo</i> and evaluation of selenium\nsupplementation in selenium-rich foods. Specifically, <b>CS-Sec</b> was constructed by grafting alkyne groups on organic small-molecule\nfluorescent probes with azide groups on azido chitosan by click chemistry.\nA 2,4-dinitrophenyl ether (DNB) with a strong intramolecular charge\ntransfer (ICT) effect was selected as a response group and fluorescence-quenching\ngroup, which had excellent chemical specificity toward Sec. In addition, <b>CS-Sec</b> has high selectivity and sensitivity toward Sec over\nother analytes, and an excellent limit of detection (LOD) is as low\nas 15 nM. Impressively, <b>CS-Sec</b> has been successfully\nused to detect and image the concentration of Sec in living HepG2\ncells and mouse models with exciting results, indicating that the\nnewly constructed <b>CS-Sec</b> can provide a robust molecule\ntool for the rapid evaluation of the selenium supplementation effect\nand imaging in the future.