Host–Guest Assembly of pH-Responsive Degradable Microcapsules with Controlled Drug Release Behavior

Biodegradable microcapsules with pH-responsibility were fabricated with host–guest interaction between β-cyclodextrin (β-CD) and adamantane (AD). Two biocompatible polymers, dextran- graft -β-CD (Dex- g -β-CD) and poly(aspartic- graft -adamantane) (PASP- g -AD), were assembled on CaCO 3 particles. Rhodamine B (Rh B) was captured in the core as a model drug. With CaCO 3 particles removed by EDTA, hollow microcapsules loaded with Rh B were obtained. As β-CD was grafted to polyaldehyde dextran (PAD) through pH-sensitive C═N bonds, the capsules could degrade and release Rh B in an acidic environment, showing a pH-sensitive release behavior. Confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) were used to characterize the capsules. In vitro drug release and degradation of the microcapsules were studied. The capsules were coincubated with HeLa cells at different pH values, further proving the controlled release behavior. In conclusion, the pH-sensitive microcapsules have great application potential in drug delivery.