Dynamic Poly(amine) Capsules with Reversible pH-Triggered Responsiveness

Microcapsules with an aqueous core and stimuli-responsive shell are attractive as delivery or collection vehicles for repeatedly or reversibly loading and unloading cargo molecules. Applications in complex scenarios often require smart capsules to respond intelligently and dynamically to environmental changes. However, dynamic capsules for release in acidic environmental conditions but blockage under neutral or basic conditions are lacking. In this work, a new design of a dynamic capsule is reported using a cross-linked poly(amine) shell to achieve reversibly pH-responsive hydrogel microcapsules. The poly(amine) hydrogel capsules exhibit dynamic swelling–shrinking behavior together with a corresponding mesh size change of the shell network upon pH switches, with the capability of cyclic capture, trap, and release of cargo molecules with size selectivity. The newly designed poly(amine) capsules enrich the diversity of the smart capsule library and broaden their potential application space.