New insights on the release and self-healing model of stimuli-sensitive liposomes

Abstract

The mixing of conventional and pH-sensitive lipids was exploited to design novel stimuli-responsive liposomes (fliposomes) that could be used for smart drug delivery. We deeply investigated the structural properties of the fliposomes and revealed the mechanisms that are involved in a membrane transformation during a pH change. From ITC experiments we observed the existence of a slow process that was attributed to lipid layers arrangement with changing pH. Moreover, we determined for the first time the pKa value of the trigger-lipid in an aqueous milieu that is drastically different from the methanol-based values reported previously in the literature. Furthermore, we studied the release kinetics of encapsulated NaCl and proposed a novel model of release that involves the physical fitting parameters that could be extracted from the release curves fitting. We have obtained for the first time, the values of pores self-healing times and were able to trace their evolution with changing pH, temperature, the amount of lipid-trigger.

Keywords: Drug delivery; Fliposomes; Liposomes; SAXS; Smart materials; Trigger lipid.