| Description |
Two polymeric systems, polyelectrolyte gel and polymer complex, were chosen to design electro-sensitive polymers and electrically modulated drug delivery systems. Physical property changes of these polymers were studied in response to an applied electric current. Feasibility studies for both the controlled release of charged solutes from crosslinked polyelectrolyte gel and release of macromolecules from polymer complexes were demonstrated. The bending of poly(2-acrylamido-2-methyl-l-propane sulfonic acid-co-n-butylmethacrylate), poly(AMPS-co-BMA), gel under an applied electric stimulus was explained by depletion polarization when the electrode is not contact with the gel. The deswelling of this gel under an applied electic stimulus was explained by electro-osmosis and local pH changes when the electrode is contact with the gel. Edrophonium chloride, a positively charged solute, was released in an on-off pattern from a poly(AMPS-co-BMA) monolithic device with electric stimulus. The on-off release mechanism of the positively charged solute was explained as an ion exchange between the solute and hydroxonium ion which was produced at the anode, followed by the release of a debound solute from the gel-Polymer complexes of Poly(ethyloxazoline)/poly(methacrylic acid), PEOx/PMAA, and poly(allylamine)/heparin were prepared by hydrogen bonding and ionic bonding respectively in order to develop an electro-erodible polymer. The complexes underwent surface erosion due to a local pH increase at the cathode when an electric stimulus was applied. The release of model macromolecules, insulin and heparin, from the complex matrices followed the pattern of an applied step function of electric stimulation. The release rate was decreased due to the depletion of loaded solute in the poly(AMPS-co-BMA) polyelectrolyte gel under an applied electric stimulus. However, the constant release rate, owing to the surface erosion mechanism, was obtained from the electro-erodible polymer complex. |
