Poly(lactic acid)/N-maleoylchitosan core-shell capsules: preparation and drug release properties.

An oil in water interface radical polymerization was used to prepare felodipine-loaded polymerized-N-maleoylchitosan (p-NMCS) and poly(lactic acid) (PLA)/p-NMCS capsules. Dynamic Light Scattering, Field Emission Scanning Electron Microscopy and Transmission Electron Microscope characterization revealed that both the p-NMCS and PLA/p-NMCS microcapsules had a ~550 nm hydrodynamic diameter, regular spherical morphology and an obvious core-shell structure. The ratio of PLA to p-NMCS in PLA/p-NMCS microcapsules was found affecting the drug loading content and entrapment efficiency. In vitro release kinetic results indicated that the p-NMCS microcapsules had a fast release rate comparing with that of the PLA/p-NMCS core-shell microcapsules, suggesting the release mechanism of the p-NMCS microcapsules was a diffusion-driven process, while the release mechanism of the PLA/p-NMCS microcapsules with high ratio of PLA to p-NMCS (not less than 1/1) was a combined diffusion and degradation-driven process.