Light-Induced Permeabilization of Liposomes with a new Porphyrin and its Chlorin and Bacteriochlorin

The intracellular delivery of therapeutic agents is a central challenge in the treatment of different diseases. Light sensitive liposomes can release their cargo with high temporal and spatial precision. The light sensitivity of the liposomes is based on incorporated photosensitizers. Since light penetration into human tissue is higher at wavelengths greater than 650 nm, we synthesized the chlorin and bacteriochlorin derivative from the new photosensitizer 5,10-Di-(4-hydroxyphenyl)-15,20-diphenyl-porphyrin. Both, chlorin and bacteriochlorin showed a higher absorption peak at 650 nm than the porphyrin. Interestingly, the bacteriochlorin showed a stable additional absorption peak at 740 nm. To investigate the potential of the derivates for light-induced release from liposomes we incorporated them into liposomes. Liposomes with the porphyrin, the chlorin and bacteriochlorin released their cargo effectively after light irradiation. Liposomes with the bacteriochlorin showed release also after irradiation at 740 nm. Additionally, we investigated the potential of the bacteriochlorin as a sensitizer for PDT. The bacteriochlorin showed good cell killing results when irradiated at 740 nm compared to the photosensitizer BPD irradiated at 690 nm. We believe that the synthesized porphyrin 5,10-DiOH and its chlorin and bacteriochlorin derivatives are interesting candidates for photodynamic applications and need further investigation.