Uptake and localisation of rhenium fac-tricarbonyl polypyridyls in fluorescent cell imaging experiments

Abstract

The synthesis of a series of rhenium fac tricarbonyl bisimine complexes and their application as lumophores in fluorescence imaging of yeast and human adenocarcinoma cells is reported. A wide range of complexes are synthesised with varying charges and lipophilicities, all of which have photophysical properties which make them suitable as cell imaging agents. After attempts to apply these as imaging agents in various strains of yeast which showed limited uptake, an investigation was undertaken of their applications as imaging agents in mammalian cells. In general the uptake was high and short-term toxicity and photobleaching appear to be low. The patterns of uptake and localisation are correlated with structural and electronic features of the complexes in an attempt to establish ground-rules for the design and application of rhenium complexes in imaging of eukaryotes.

Re(I) carbonyl complexes: Multimodal platforms for inorganic chemical biology

“…This organelle specificity is thought to be due to the greater transmembrane potential of the inner mitochondrial membrane that attract positively charged lipophilic molecules. A similar complex bearing a hydroxymethyl group (1, R = OH) displayed a very similar localization pattern in MCF-7 cells, despite the apparent lack of a thiol-reactive group, supposedly necessary to anchor the complex to the organelle [40]. To explain this, it was postulated that phosphorylation of the internalized complex could lead to a thiol-reactive moiety, although no experimental evidence for this hypothesis was obtained.…”

“…Coogan and co-workers synthesized a range of Re(I) tricarbonyl polypyridyl complexes varying in charge, size and lipophilicity in a first attempt to rationalize the cell localization of such compounds [40]. Although rationalization proved sometimes difficult, they could observe for instance that compound 2 ( Figure 3) was localized at the plasma membrane of MCF-7 cells, probably interacting with the cationic residues of the glycoproteins layers (glycocalyx).…”

“…The isothiocyanate-functionalized complexes 38 (Figure 15), bearing various bidentate ligands, were coupled to HSA [33]. Similarly, thiol-reactive groups such as iodoacetamide (39, Figure 15) and maleimide (40) have been appended to Re(I) tricarbonyl complexes. Compound 39 was successfully used to label HSA, with a final dye:protein ratio of 0.7 [109].…”

“…This is generally done by tuning the structure of the N^N ligand, since it is involved in the MLCT. Two families of ligand have been particularly explored: (i) polypyridyl ligands, mostly derived from 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen) [19][20][21][23][24][25][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] and (ii) bis-quinoline and its derivatives, e.g. bis(phenanthridinylmethyl)amine (bpm) [22,[43][44][45].…”

Intracellular oxygen: Similar results from two methods of measurement using phosphorescent nanoparticles

“…Exceptionally longlived°uorescent states such as this have been employed for O 2 -mapping in living cells, e.g., in cultured cells of mouse liver by the use of quantitative°uorescence microscopy, 24 and in Amoeba proteus. 25 The even longer lifetimes provided by O 2 -quenchable phosphorescent luminophores, [26][27][28][29] together with their other desirable photophysical properties, [30][31][32][33][34][35] make them substances of choice for a burgeoning body of applications.…”