(54b) Asymmetric Microcapsules for Osmotic Pressure Triggered Release of Biomolecules

Microcapsules with asymmetric shell thickness are fabricated using a microfluidic approach to encapsulate various biomolecules for osmotic pressure triggered release. The inhomogeneity of shell thickness can be controlled by tuning the flow rate ratios of the middle phase to the inner phase. This study demonstrates the swelling of these asymmetric microcapsules begins at the thinnest part of the shell and eventually leads to rupture at the weak spot with low osmotic pressure. Systematic studies indicate the rupture fraction of these microcapsules increases with increasing inhomogeneity, while the rupture osmotic pressure decreases linearly with increasing inhomogeneity. The asymmetric microcapsules are demonstrated to be impermeable to small probe molecules, which enables long-term storage. Thus, these microcapsules can be used for the long-term storage of biomolecules, such as enzymes, which can be controllably released through osmotic shock without impairing their biological activity. The study provides a new approach to design effective carriers to encapsulate biomolecules and release them on-demand upon applying osmotic shock.