Two-photon microscopy study of the intracellular compartmentalisation of emissive terbium complexes and their oligo-arginine and oligo-guanidinium conjugates

An emissive terbium complex has been conjugated to a C-12 chain, Lys-Arg(7), Arg(7), a tetraguanidinium cation and human serum albumin; two-photon excitation at 720 nm facilitated microscopy studies revealing cell localisation profiles with the oligo-guanidinium conjugate localising in mitochondria but causing apoptotic cell death (IC(50)12 mu M), the C-12-amide complex giving rise to necrotic cell death in skin fibroblasts (IC50 8 mu M) and the peptide conjugates and the methyl ester generating punctuate cytosolic intracellular distributions.