Manganese oxide doped carbon dots for temperature-responsive biosensing and target bioimaging.

We report on the synthesis of manganese oxide doped CDs (MnO x -CDs) by a hydrothermal strategy using manganese (III) acetylacetonate (Mn(III) (C 5 H 7 O 2) 3) as the only raw materials. The MnO x -CDs exhibit water solubility, favorable biocompatibility, low cytotoxicity, and show blue fluorescence with excitation/emission maxima at 326/442 nm with a quantum yield of 11.3%, allowing efficient cellular imaging. The MnO x -CDs have a reversible temperature-sensitive fluorescent property in vitro within 10–60 °C, which can also be used as a sensitive thermometer in living cells. By a scratch assay, the MnO x -CDs can restrain the migration of HepG2 cancer cells, which make the MnO x -CDs be attractive candidates for liver cancer adjuvant treatment. Besides, the fluorescence of the MnO x -CDs is quenched in the presence of Fe3+ due to the formation of a nonfluorescent MnO x -CDs-Fe3+ complex between oxygen-containing groups on the surface of MnO x -CDs and Fe3+, and the quenched fluorescence of MnO x -CDs can be turn-on by dissociation of MnO x -CDs-Fe3+ complexes by biothiols including L -cysteine, homocysteine and glutathione. Therefore, the Fe3+ and biothiols can be sequentially detected with high reliability and accuracy via exploiting the on-off-on nanosensor at room temperature, respectively. Further application to detection biothiols in human serum indicated that the probe was practicality and feasibility in medical field. Image 1 • First synthesis of manganese oxide doped CDs (MnO x -CDs) using manganese (III) acetylacetonate as the single precursor. • The MnO x -CDs have reversible temperature-sensitive fluorescent behaviors in vitro and can be used as a thermometer in vivo. • The MnO x -CDs can restrain the migration of HepG2 cancer cells, which facilitate liver cancer adjuvant treatment. • Fe3+ and biothiols can be sequentially detected with high reliability and accuracy based on the MnO x -CDs. [ABSTRACT FROM AUTHOR]