(29e) Electrically Induced Controlled Release from Biopolymer Capsules

Applications such as drug delivery and directed catalysis require the design of container structures exhibiting controlled release in response to various external stimuli. Here, we explore the possibility of using an electric field to induce release from a class of capsules. Electric fields can be attractive because they can be easily controlled and generally give rise to a faster response. Currently, most of the electrically-actuated systems in the literature need either conducting polymers or synthetic polyelectrolyte gels, thereby limiting their application. We present and analyze the electro-induced bursting and release profiles of capsules made from common biopolymers. These capsules are formed by a simple procedure involving electrostatic coacervation. In the presence of an electric field, the combination of osmotic pressure differences, local pH changes, and electrophoretic movement leads to the deformation and bursting of the capsules. We have conducted systematic experiments to decouple these phenomena and identify their individual roles. The utility of these capsules is studied by encapsulating model solutes in their interior and characterizing the release of solute into the external solution under different voltages.