Core−Shell Chitosan Microcapsules for Programmed Sequentialdrug Release

A novel type of core-shell chitosan microcapsules with programmed functions of sequential drug release are designed and developed by microfluidic technology for acute gastrosis therapy. The microcapsule is composed of a cross-linked chitosan hydrogel shell and an oil core containing both free drug molecules and drug-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles. The resultant microcapsules can keep structural integrity in neutral medium without leakage of encapsulated substances. Based on the acid-triggered decomposition of chitosan shell and the sustained release of drug from PLGA nanoparticles, our proposed microcapsules successfully achieve the programmed sequential drug release performance, i.e., burst release first and then sustained release. In acid medium, the encapsulated free drug and drug-loaded PLGA nanoparticles can be rapidly released within 60 s to achieve the first burst-release. Later, the drugs loaded in PLGA nanoparticles are slowly released for a few days to achieve the second sustained-release due to the synergistic effect of drug diffusion and PLGA degradation. Such core-shell chitosan microcapsules with programmed functions of sequential drug release are promising to achieve a more rational drug delivery and controlled-release for the treatment of acute stomach illness. In addition, the designed strategy of programmed sequential release in this work is of versatility for various biomedical applications.