Photoresponsive liposomes and LipoParticles by incorporating a photosensitizer agent in their lipid membrane

Abstract

Liposomes, as self-assembled lipid layer vesicles, have emerged as a promising platform for various biomedical applications such as photodynamic therapy (PDT). LipoParticles are core–shell lipid assemblies with a solid polymer core coated by a lipid membrane, which gather the advantages of both their counterparts. Photosensitizers (PS), used in PDT, are photosensitive molecules than can be activated by an exposure to a light source, leading to the death of pathogenic surrounding cells. In this context, the aim of this study is to elaborate liposomes and LipoParticles incorporating a PS, and to examine their resulting photoresponsive properties by following the release, triggered by an UV irradiation, of incorporated fluorescent (macro)molecules. Al(III) phthalocyanine chloride disulfonic acid (AlPcS2) was chosen as PS, and the release of 5(6)-carboxyfluorescein (CF) or bovine serum albumin conjugated with fluorescein isothiocyanate (BSA-FITC) from liposomes and poly (lactic-co-glycolic acid) (PLGA) core of LipoParticles respectively, was investigated by fluorescence spectroscopy. The results have shown that UV irradiation led to the release of CF molecules depending on the membrane lipid formulation, and that repeated irradiations could increase the amount of CF molecules released from liposomes. The main parameters governing the release of BSA-FITC macromolecules from LipoParticles were the temperature of their elaboration (corresponding to a reorganization of several liposomes on the surface of PLGA particles), the initial PS concentration, and the duration of UV irradiation. Best results were found with a temperature of the LipoParticles elaboration of 20 °C, a PS concentration of 0.1 mM, and a duration of irradiation of 5 min. These results support the fact that similarly to liposomes, LipoParticles can also be endowed with photoresponsive properties, which positions them as interesting nanovectors for PDT.