Photo-triggerable liposomal drug delivery systems: from simple porphyrin insertion in the lipid bilayer towards supramolecular assemblies of lipid-porphyrin conjugates.

Light-responsive liposomes are considered nowadays as one of the most promising nanoparticulate systems for the delivery and release of an active pharmaceutical ingredient (API) in a spatio-temporal manner. Several strategies can be used to design photo-triggered liposomes. One of them consists in the incorporation of a photosensitizer (PS) in the lipid matrix of a liposomal bilayer that induces the release of the cargo either via a photochemical or a photophysical process. Among the described photosensitizers, porphyrin derivatives have appeared as the most potent ones. This review describes the state-of-the-art of photo-triggerable liposomes based on the combination of lipids and porphyrin derivatives either free or conjugated. It focuses on the different light-triggered release mechanisms and the requirements for the development of such systems. It also details the different strategies for the synthesis of lipid-porphyrin conjugates, their self-assembling properties and their biomedical applications.