Solute Release from Polymer Capsules Loaded With Liposomes

Abstract

Polymer capsules and lipid vesicles (liposomes) are two types of containers that have been extensively studied for their applications in drug delivery. In this thesis, we explore a hybrid of these two structures (i.e. polymer capsules bearing encapsulated liposomes) and study the release of solute from these structures. The capsules are made by contacting the anionic biopolymer alginate with multivalent cations such as calcium (Ca2+) or holmium (Ho3+), which crosslink the alginate chains. Liposomes prepared from conventional phospholipids are loaded with a model solute (an aromatic dye) and then encapsulated in the alginate capsules. We study the effects of different variables on solute release, including the capsule size and architecture, crosslinking ion type and concentration, and crosslinking time. In addition, we compare release from the bare capsules (not containing liposomes) with that from capsules containing liposomes. A key finding is that the latter releases solute over a much longer time compared to the former. Overall, the results from this study will guide the design of new structures for drug delivery applications.