A sensitive "Switch-on" phosphorescent probe for ferrous iron quantification in drug and In vitro imaging of living cells.

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 (Fe). In the current study, a novel turn-on phosphorescent probe for Fe quantification and visualization has been proposed based on the hybrid nanocomposite of manganese dioxide and gemini iridium complex (MnO-GM-Ir). The surfactant-like GM-Ir with positive charges was beneficial to combine with the negatively charged manganese dioxide (MnO) nanosheets, and thus endowing the MnO-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 MnO nanosheets through fluorescence resonance energy transfer (FRET) and the inner filter effect (IFE), while the phosphorescence could be significantly recovered in the presence of Fevia a selective Fe-mediated reduction of MnO nanosheets, indicating a highly-specific selectivity towards Fe with a low detection limit (80 nM). The drug test assay and in vitro imaging studies further proved that the MnO-GM-Ir nanocomposite could be employed as a promising probe for the quantitative detection of exogenous Fe in drug and in vitro imaging of living cells.