Mitochondria-targeting properties and photodynamic activities of porphyrin derivatives bearing cationic pendant

Four meso-tetraphenylporphyrin derivatives bearing either triphenylphosphonium ion-(P1 and P2) or triethylammonium ion-(P3 and P4) terminated alkoxy group at either para-(P1 and P3) or meta-(P2 and P4) position of one meso-phenyl group were designed and synthesized. P1–P4 show similar absorption and fluorescence emission spectra and 1 O 2 quantum yields. The more lipophilic nature of triphenylphosphonium ion over triethylammonium ion renders P1 and P2 higher octanol/water partition coefficients than P3 and P4. Confocal fluorescence microscopy proved that P1–P4 are all mitochondria-targeting. MTT assay showed that P1–P4 presented significant phototoxicity at the concentrations that dark toxicity is negligible towards human breast cancer cell line MCF-7 cells, displaying their application potential in PDT.