Hydrogel formation of the pH response polymer polyvinylacetal diethylaminoacetate (AEA)

The effects of pH and temperature on hydrogel formation of polyvinylacetal diethylaminoacetate (AEA) and drug release were examined. When a dialysis tube containing AEA dissolved in pH 4 solution was immersed in phosphate buffer pH 7.4 at 37 degrees C, AEA hydrogel was formed inside the tube and drug release became slow. Various porous structures in the inner region of hydrogel were observed by Scanning Electron Microscopy. The effects of temperature change on lattice distance of hydrogel were determined by dynamic light scattering. The average pore size of AEA hydrogel was also determined by the release of FITC-dextrans of various molecular weights from AEA hydrogel. AEA solution with low viscosity at pH 4 but which form hydrogel at neutral pH condition has the potential for use in controlled release of drugs applied to physiological membranes. (C) 1998 Elsevier Science B.V. All rights reserved.