A highly selective turn-on fluorescent probe for iron(ii) to visualize labile iron in living cells

Abstract

Although labile iron plays critical roles in diverse biological processes in living cells, the physiological and pathophysiological functions of iron have not been sufficiently explored, partially due to a lack of methods for visualizing intracellular labile iron. In this edge article, we present a novel turn-on fluorescent probe (RhoNox-1) for the selective detection of Fe 2+ based on N-oxide chemistry.Spectroscopic studies combined with DFT calculations and electrochemical studies revealed that fluorescence quenching of RhoNox-1 occurred in physiological conditions, which was attributed to nonradiative deactivation of the excited state of tertiary amine N-oxide substituted xanthene involving a twisted internal charge transfer (TICT) process and partially due to photo-induced electron transfer (PET) from the N-oxide group. RhoNox-1 showed significant enhancement of the fluorescence signal in Fe 2+loaded cells via selective Fe 2+ -mediated deoxygenation of the N-oxide group and also successfully detected basal and endogenous labile Fe 2+ in living cells.

Plasma-activated medium induces A549 cell injury via a spiral apoptotic cascade involving the mitochondrial–nuclear network

“…The air/liquid boundary is known to be an important site for the production and transport of reactive species generated by plasma irradiation [16]. BP is a chelator specific for Fe 2+ and has been reported to decrease intracellular Fe 2+ concentrations [37]. BP attenuated cell injury in the present study ( Fig.…”

Distinct iron architecture in SF3B1-mutant myelodysplastic syndrome patients is linked to an SLC25A37 splice variant with a retained intron

“…RhoNox-1 was prepared in-house by chemical modification of commercial rhodamine B as previously described in order to selectively detect Fe 2 þ . 15 For the experiment conducted with RhoNox-1, 3 Â 10 5 BMMNCs were incubated in Iscove's modified Dulbecco's serumfree medium with FeO 4 S (100 mM) for 30 min at 37 1C, 5% CO 2 . After incubation, cells were washed and incubated with RhoNox-1 (2 mM) for 30 min at room temperature.…”

A Bioorthogonal Reaction of N‐Oxide and Boron Reagents

“…Focusing first on the former, the reaction could indeed be accelerated by turning to N , N -dialkylaryl N -oxides, which produce superior leaving groups compared to trialkylamines. [21] Kinetic parameters for this reaction were measured by employing a fluorogenic N , N -dialkylaryl N -oxide 6 , [22] obtained through m CPBA-mediated oxidation of the parent rhodol fluorophore. [23] The reaction of N -oxide 6 with phenylboronic acid in phosphate-buffered saline (PBS, pH 7.4) proceeded with a second-order rate constant of 1.28 ± 0.11 × 10 −3 M −1 s −1 (Fig.…”