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

Abstract

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.