Fluorescent probes for iron, heme, and related enzymes

Abstract Iron is the most abundant transition metal in the human body, and it has a crucial role in a variety of biological functions. Its unique redox capability endows it with the ability to perform diverse biological functions, but it can also induce cell damage via the generation of reactive oxygen species through the well-known Fenton reaction. Iron overload and iron deficiency are both detrimental for human cells. In living cells, only a small fraction of iron exists in ionic form (Fe2+ and Fe3+) or is weakly bound to cellular ligands, and these groups are known as the labile iron pool. Cells maintain this pool through specialized transport and storage proteins. The majority of biological iron is tightly housed in heme, proteins, heme iron enzymes, and non-heme iron enzymes, which play an important part in various biological processes, including drug metabolism and the synthesis of steroid hormones. Therefore, tools for the effective monitoring of iron, heme, and relative species allow the development of an understanding of their pathological and non-pathological physiological functions. This paper summarizes recent developments in molecular fluorescent probes for the detection of iron and relative species, including Fe2+, Fe3+, heme, and related enzymes, as well as their applications in bioimaging of living cells and in vivo.