Self-Assembled Polymer Membrane Capsules Inflated by Osmotic Pressure

Author :Vernita D. Gordon, Xi Chen, John W. Hutchinson, Andreas R. Bausch, Manuel Marquez, and David A. Weitz
Publication :JACS
Publisher :American Chemical Society
Volume :126
Pages :14117-14122
Year :2004

We fabricate and characterize capsules that are composite membranes, made of a polymer
network stabilized by adsorption to colloids and inflated by osmotic pressure from internal free polyelectrolyte; here, poly-L-lysine forms the network and inflates the capsules. To assess these capsules’ properties and structure, we deform capsules using microcantilevers and use finite element modeling to describe these deformations. Additional experimental tests confirm the model’s validity. These capsules’ resilient response to mechanical forces indicates that loading and shear should be good triggers for the release of contents via deformation. The osmotic pressure inflating these capsules has the potential to trigger release of contents via deflation in response to changes in the capsules’ environment; we demonstrate addition of salt as a
trigger for deflating capsules. Because these capsules have a variety of release triggers available and the technique used to fabricate them is very flexible and allows high encapsulation efficiency, these capsules have very high potential for application in many areas.