Photo-cured pH-responsive polyampholyte-coated membranes for controlled release of drugs with different molecular weights and charges

Intelligent drug delivery membranes were synthesised by photocuring poly(acrylic acid) (PAA) or polyampholytes comprised of copolymers of acrylic acid (AA)/2-(diethylamino)ethyl methacrylate (DEAEMA) with varying monomeric compositions onto poly(2-hydroxyethyl methacrylate) (PHEMA) membranes, each with model drugs of different molecular weights and charges being incorporated. pH-responsive release behaviours of the model drugs which included methylene blue (cationic), metanil yellow (anionic) and caffeine (neutral) were studied. Only membranes with methylene blue and caffeine incorporated displayed clear pH-responsive releases though all coatings. This study demonstrates that drug diffusion through pH-responsive membranes depends to a large extent on the attractive interaction between the drug and the appropriate functional group/s in the coating