Iron plays an important role in various physiological processes. However, the detailed biological functions of iron have not been sufficiently explored because of a lack of effective methods to monitoring iron, especially the labile ferrous ion (Fe2+). In the current study, a novel turn-on phosphorescent probe for Fe2+ quantification and visualization has been proposed based on the hybrid nanocomposite of manganese dioxide and gemini iridium complex (MnO2-GM-Ir). The surfactant-like GM-Ir with positive charges was beneficial to combine with the negatively charged manganese dioxide (MnO2) nanosheets, and thus endowing the MnO2-GM-Ir nanocomposite excellent dispersion ability in the water as well as efficiently avoiding the interference to the detection caused by the agglomeration of nanocomposite. Phosphorescence of GM-Ir was effectively quenched by MnO2 nanosheets through fluorescence resonance energy transfer (FRET) and the inner filter effect (IFE), while the phosphorescence could be significantly recovered in the presence of Fe2+via a selective Fe2+-mediated reduction of MnO2 nanosheets, indicating a highly-specific selectivity towards Fe2+ with a low detection limit (80 nM). The drug test assay and in vitro imaging studies further proved that the MnO2-GM-Ir nanocomposite could be employed as a promising probe for the quantitative detection of exogenous Fe2+ in drug and in vitro imaging of living cells.
Keywords: Aqueous solubility; Fe(2+) detection; Gemini-iridium complex; Imaging; MnO(2) nanosheet.
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