pH-sensitive interpenetrating network hydrogels based on chitosan derivatives and alginate for oral drug delivery.

Methoxy poly (ethylene glycol) grafted carboxymethyl chitosan (mPEG-g-CMC) and alginate were chosen as the constituents of hydrogel beads for the construction of an interpenetrating polymeric network matrix. A contrast study between the mPEG-g-CMC hydrogel and mPEG physically mixed with CMC hydrogel was carried out. Bovine serum albumin (BSA) as a model for a protein drug was encapsulated in the hydrogel network, and the drug release properties were studied. The hydrogels prepared by these two methods maintained good pH sensitivity; the loading capacity of the mPEG-g-CMC/alginate hydrogel was enhanced in comparison with that of the hydrogel prepared by physically mixing mPEG. The burst release of the protein was slightly decreased at pH 1.2, while the release at pH 7.4 was improved, suggesting that the mPEG-g-CMC/alginate pH-sensitive hydrogel will be promising for site-specific protein drug delivery in the intestine.