The authors have encapsulated in the cavity of [Ru6(p-iPrC6H4Me)6(tpt)2-(C6H2O4)3]6+ (tpt = 2,4,6-tris(pyridin-4-yl)-1,3,5-triazine), and intrinsically fluorescent pyrenyl compd. (pyrene-R = 1-(4,6-dichloro-1,3,5-trianzin-2-yl)pyrene), thus giving rise to the hexanuclear metalla-prism, in which the pyrenyl deriv. occupies the cavity of [Ru6(p-iPrC6H4Me)6(tpt)2-(C6H2O4)3]6+. Once inside a tumor cell the hexaruthenium chage releases the fluorescent guest. Microscopy and flow cytometry could be used to monitor the uptake of the fluorophores into human ovarian carcinoma cells. The uptake was probably by assisted diffusion.