Chemical tools for detecting Fe ions

Abstract

Owing to its distinctive electrochemical properties with interconvertible multiple oxidation states, iron plays a significant role in various physiologically important functions such as respiration, oxygen transport, energy production, and enzymatic reactions. This redox activity can also potentially produce cellular damage and death, and numerous diseases are related to iron overload resulting from the dysfunction of the iron regulatory system. In this case, “free iron” or “labile iron,” which refers to iron ion weakly bound or not bound to proteins, causes aberrant production of reactive oxygen species. With the aim of elucidating the variation of labile iron involved in pathological processes, some chemical tools that can qualitatively and/or quantitatively monitor iron have been utilized to investigate the distribution, accumulation, and flux of biological iron species. Since iron ions show unique reactivity depending on its redox state, i.e., Fe2+ or Fe3+ (or transiently higher oxidative states), methods for the separate detection of iron species with different redox states are preferred to understand its physiological and pathological roles more in detail. The scope of this review article covers from classical chromogenic to newly emerging chemical tools for the detection of Fe ions. In particular, chemical tools applicable to biological studies will be presented.

Ferroptosis: A Regulated Cell Death Nexus Linking Metabolism, Redox Biology, and Disease

“…The former can be detected using inductively coupled plasma-MS or calcein AM quenching, as well as other specific iron probes (Hirayama and Nagasawa, 2017; Spangler et al, 2016), while the latter can be detected using phosphatidylcholine hydroperoxide reduction in cell lysates using LC-MS (Yang et al, 2014). …”

A universal fluorogenic switch for Fe(ii) ion based on N-oxide chemistry permits the visualization of intracellular redox equilibrium shift towards labile iron in hypoxic tumor cells

“…Recently, several redox state-selective fluorescent probes for Fe 2+ with a turn-on readout have been developed. 30 RhoNox-1, reported by our group, is the first example of detection of labile iron in live cells with a turn-on response, where N-oxide acts as a selective fluorogenic switch to Fe 2+ . 31 Subsequently, Chang et al reported IP-1 on the basis of a chelation-assisted oxidative C–O bond cleavage, which was successfully applied to detection of biologically stimulated accumulation of labile iron.…”

Novel probes for selective fluorometric sensing of Fe(II) and Fe(III) based on BODIPY dyes

“…It has crucial roles in oxygen uptake, oxygen metabolism, electron transfer, and transcriptional regulation and a possible disorder in Fe ion metabolism cause several diseases (5,6). Thus, detection of Fe ions is useful in a wide range of area, including clinical diagnostics, therapeutic monitoring, and detection of organisms and toxins (7). Numerous research studies have been devoted on the development of Fe 2+ and/or Fe 3+ chemosensors (8).…”