Enzymatic degradation of Hyaluronic acid/Poly-l-Lysine capsules for burst drug release

The aim of this study is to investigate the process by which multilayer polyelectrolyte microcapsules rupture under the action of enzymes to which the polyanion or polycation is sensitive. The capsules were prepared using a template of alginate microspheres cross-linked with calcium ions, which liquefy after the capsule has formed. The capsules are obtained via a layer-by-layer, LbL process using poly-l-lysine (PLL) as the polycation and hyaluronic acid (HA) as the polyanion. The rupture process of the capsules has been studied in media containing pronase, to which PLL is sensitive, hyaluronidase, to which HA is sensitive, or a mixture of both. The kinetics of capsule rupture are monitored by observation and counting the remaining microcapsules under a stereomicroscope or by quantifying the release of alginate into the medium. At the same time, the change in size of the microcapsules that remain intact is measured through optical microscopy, noting that the elasticity of the membrane produced by LbL allows them to swell to double their diameter before rupturing.