Harnessing Interfacial Phenomena to Program the Release Properties of Hollow Microcapsules

The generation of near-infrared (NIR)-sensitive microcapsules is presented and it is demonstrated that the release properties of these microcapsules can be tailored by controlling their morphology. A biocompatible polymer, poly(DL-lactic-co-glycolic)acid (PLGA) is used to form hollow microcapsules from monodisperse water-in-oil-in-water (W/O/W) double emulsions. Both the composition of PLGA and the oil phase of W/O/W double emulsions significantly affect the morphology of the subsequently formed microcapsules. PLGA microcapsules with vastly different morphologies, from spherical to snowman-like capsules, are obtained due to changes in the solvent quality of the oil phase during solvent removal. The adhesiveness of the PLGA-laden interface plays a critical role in the formation of snowman-like microcapsules. NIR-sensitive PLGA microcapsules are designed to have responsive properties by incorporating Au nanorods into the microcapsule shell, which enables the triggered release of encapsulated materials. The effect of capsule morphology on the NIR responsiveness and release properties of PLGA microcapsules is demonstrated.