Liposomes have been widely studied in recent years to enhance their properties as a supramolecular drug delivery platform. A key point of advancing liposomal drug delivery would be to control the timing and location of cargo release to maximize drug potency and minimize side effects. Commonly studied triggered release approaches exploit stimuli including pH (passive) and light (active). Here, we present a novel approach for triggering release of contents from liposomes driven by increased calcium at target sites, which plays an important role in biology related to certain diseases. Firstly, a switchable lipid 1 sensitized to calcium was synthesized and incorporated into liposomes. This lipid trigger has a well-known calcium binding headgroup that can induce a conformational change that perturbs liposome membrane integrity and thereby cause content release upon calcium binding. This was proven by fluorescent dye release assays via dose-dependent response correlating with the percentage of 1 in liposomes. Corresponding dynamic light scattering experiments indicated dramatic changes in particle size upon adding calcium to liposomes containing 1. In selectivity studies, calcium provided the greatest release compared to nine other naturally occurring metal cations. Finally, STEM was used to visualize liposome morphology upon treatment of liposomes containing 1 with calcium and significant changes were observed. All of these results showcase lipid switches driven by molecular recognition principles as an exciting avenue for controlling liposome release.

Calcium-triggered release of contents from liposomes for drug delivery applications

2019 Spring National Meeting

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