Phosphorescence imaging of living cells with amino acid-functionalized tris(2-phenylpyridine)iridium(III) complexes.
A series of nine luminescent cyclometalated octahedral iridium(III) tris(2-phenylpyridine) complexes has been synthesized, functionalized with three different amino acids (glycine, alanine, and lysine), on one, two, or all three of the phenylpyridine ligands. All starting complexes and final compounds have been fully analyzed by one-dimensional (1D) and two-dimensional (2D) NMR spectroscopy, and photophysical data have been obtained for all the mono-, bis-, and tri- substituted iridium(III) complexes. Cellular uptake and localization have been studied with flow cytometry and confocal microscopy, respectively. Confocal experiments demonstrate that all nine  substituted iridium(III) complexes show variable uptake in the tumor cells. The monosubstituted iridium(III) complexes give the highest cellular uptake, and the series substituted with lysines shows the highest toxicity. This systematic study of amino acid-functionalized Ir(ppy)(3) complexes provides guidelines for further functionalization and possible implementation of luminescent iridium complexes, for example, in (automated) peptide synthesis or biomarker specific targeting.
Supramolecular Chemistry and Technology, MESA+ Institute for Nanotechnology,  University of Twente , P.O. Box 217, 7500 AE, Enschede, The Netherlands.
Peter
P
Steunenberg
Albert
A
Ruggi
Nynke S
NS
van den Berg
Tessa
T
Buckle
Joeri
J
Kuil
Fijs W B
FW
van Leeuwen
Aldrik H
AH
Velders
D000596:Amino Acids / Q000032:analysis* / Q000138:chemical synthesis / Q000378:metabolism; D000818:Animals; D045744:Cell Line, Tumor; D002463:Cell Membrane Permeability; D002470:Cell Survival; D005434:Flow Cytometry; D049449:Luminescence; D049408:Luminescent Agents / Q000032:analysis* / Q000138:chemical synthesis / Q000378:metabolism; D051379:Mice; D018613:Microscopy, Confocal; D009942:Organometallic Compounds / Q000032:analysis* / Q000138:chemical synthesis / Q000378:metabolism
D000596:Amino Acids; D049408:Luminescent Agents; D009942:Organometallic Compounds; C520414:tris(2-phenylpyridine)iridium(III)