Light-induced permeabilization of liposomes

A central challenge in the treatment of different diseases is the delivery of therapeutic agents to a specific cellular site. Liposomes that can release their cargo upon an externally controlled trigger are attractive candidates for localized drug release. Light as external trigger can be controlled temporal and spatial with high precision. In this study, we investigate the potential of light sensitive liposomes with four different photosensitizers for light-induced release. To demonstrate permeabilization of the liposomes, we encapsulated calcein in high concentration inside liposomes, that calcein fluorescence is quenched. If calcein is released from the liposome, quenching is diminished and the fluorescence increases. We demonstrated that liposomes with the sensitizers Benzoporphyrine derivative monoacid (BPD), chlorine e6 (Ce6), Al(III) Phthalocyanine chloride disulfonic acid (AlPcS2) and a di-hydroxyphenyl porphyrine (5,10-DiOH) release cargo effectively after irradiation. Liposomes with 5,10-DiOH showed a quicker release compared to the other sensitizers. Further we observed through fractionated irradiation, that most of the release took place during light irradiation, while the permeability of the liposome decreased shortly after light exposure.