Photophysical, Cellular‐Uptake, and Bioimaging Studies of Luminescent Ruthenium(II)–Polypyridine Complexes Containing a d‐Fructose Pendant

Abstract

Two luminescent ruthenium(II)–polypyridine complexes, appended with a d‐fructose unit, [Ru(N^N)2(bpy‐fructose)](PF6)2 [bpy‐fructose = 4‐(1‐deoxy‐d‐fructos‐1‐yl)aminocarbonyl‐4′‐methyl‐2,2′‐bipyridine; N^N = 4,7‐diphenyl‐1,10‐phenanthroline (Ph2‐phen) (1a) and 2,2′‐bipyridine (bpy) (2a)] and their d‐fructose‐free counterparts [Ru(N^N)2(bpy‐Et)](PF6)2 [bpy‐Et = 4‐(ethylaminocarbonyl)‐4′‐methyl‐2,2′‐bipyridine; N^N = Ph2‐phen (1b) and bpy (2b)] are synthesized and characterized. The photophysical properties, lipophilicity, cytotoxicity, and cellular uptake of the complexes are studied. Laser‐scanning confocal microscopy reveals that both complexes 1a and 1b display intense membrane staining toward human breast adenocarcinoma (MCF‐7) cells. However, while complex 1a retains its membrane‐staining characteristic when incubated with human cervical epithelioid carcinoma (HeLa) cells, complex 1b is localized in the mitochondria. Additionally, fructose‐dependent cellular‐uptake experiments suggest that complex 1a is transported into MCF‐7 cells through a glucose transporter (GLUT) mediated pathway.