Rhenium carbonyl complexes bearing methylated triphenylphosphonium cations as antibody-free mitochondria trackers for X-ray fluorescence imaging

Abstract

Synchrotron Radiation X-ray Fluorescence (SXRF) imaging is a powerful technique for the visualization of metal complexes in biological systems. However, due to the lack of an endogenous elemental signature for...

Cellular Detection of a Mitochondria Targeted Brominated Vinyl Triphenylamine Optical Probe (TP−Br) by X‐Ray Fluorescence Microscopy

“…A copper catalyzed azide alkyne cycloaddition (CuAAC) between compound 7 and ethynyl pyridine 8 followed by counter ion exchange (iodide to chloride) on resin generated the pyridine−triazole (pyta) ligand 9 . The rhenium tricarbonyl complex TP−RePyta was finally obtained using rhenium pentacarbonyl chloride in classical coordination conditions [20,26] …”

“…The conjugation of TPÀ 2Bzim with the ReÀ Pyta moiety seems detrimental to the mitochondrial targeting. This is quite unexpected as recent work from Bertrand et al [20] demonstrated that the conjugation of a ReÀ Pyta probe with triphenyl phosphonium (TPP) cations retained the mitochondrial targeting of these TPPs. We then conducted colocalization experiments with both probes and LysoTracker Red.…”

“…[19] We recently described rhenium carbonyl complexes conjugated to mitochondria-targeting triphenyl phosphonium cations as antibody-free mitochondria trackers for SXRF imaging. [20] In the present work, we designed two bimodal probes suitable for fluorescence (two-photon excitation) and SXRF imaging based on the cationic vinyl triphenylamine TPÀ 2Bzim (Figure 1) for mitochondria targeting. We aim at developing low molecular weight organelle-specific probes suitable for SXRF imaging while gaining new insights into the cellular distribution of TPÀ 2Bzim.…”

“…Rhenium complexes of general formula [Re(N N)(CO) 3 X] n+ , with (N N) a bidentate ligand with low lying π* orbitals and X an axial ligand, display interesting features such as high stability, cell penetration abilities, luminescence emission with large Stokes shift, that have stimulated a strong interest in bio‐imaging [22] . We have described fluorescence and IR correlative imaging studies using SCoMPIs [23] and their imaging by SXRF, as mentioned above [15,16b,20] . In an alternative strategy involving a minor modification of the vinyltriphenylamine core, a bromine atom that allows exploiting the capabilities of X‐ray fluorescence [24] was introduced on the third branch of the triphenylamine core leading to the TP−Br probe.…”

“…Correlative imaging studies with synchrotron X‐ray fluorescence and fluorescence imaging have focused on labelling the organelles with a conventional marker and correlating it with X‐ray fluorescence information obtained [17c] or with a rhenium complex bearing both modalities [19] . We recently described rhenium carbonyl complexes conjugated to mitochondria‐targeting triphenyl phosphonium cations as antibody‐free mitochondria trackers for SXRF imaging [20] …”