Mercury Ions Mediated Phosphorus Containing Carbon Dots as Fluorescent Probe for Biothiols Screening.

In this study, we report the mercury ions (Hg 2 + ) mediated phosphorus-containing carbon dots (PCDs) as a selective "off–on" fluorescence probe for glutathione (GSH), cysteine (Cys) and homocysteine (Hcys). PCDs obtained by hydrothermal reaction are sensitive to Hg 2 + ions and its fluorescence can be significantly quenched owing to the electron transfer from the lowest unoccupied molecular orbital (LUMO) of PCDs to Hg 2 + . Interestingly, the weak fluorescence of Hg 2 + -mediated PCDs could be gradually recovered with the addition of GSH, Cys and Hcys. This can be attributed to the formation of Hg 2 + –S complex due to the super affinity of Hg 2 + –sulfydryl bond. The formation of Hg 2 + –S complex extremely reduces the oxidation ability of Hg 2 + that inhibits the electron transfer from LUMO of PCDs to Hg 2 + and re-opens the native electron transition from LUMO to the highest occupied molecular orbital (HOMO) of PCDs. Thus, the green fluorescence of PCDs is switched on. Furthermore, the present Hg 2 + -mediated PCDs assay exhibits a high selectivity for GSH, Cys and Hcy and has been successfully used to detect the total biothiols content in human urine samples. Hg2+-mediated phosphorus containing carbon dots (PCDs) are developed for screening biothiols. The probing assay working in photoluminescence "off-on" mode exhibits the high selectivity to biothiols and is successfully used in detecting the total biothiols content in human urine samples. [ABSTRACT FROM AUTHOR]