Effect of Sodium Alginate on the Properties of Thermosensitive Hydrogels

Sodium alginate ( SA ) was combined with poly( N ‐isopropylacrylamide) ( PNIPAAm ) to prepare thermosensitive hydrogels through semi‐interpenetrating polymer network (semi‐ IPN ) and fully interpenetrating polymer network (full‐ IPN ). The thermosensitive, swelling, mechanical, and thermal properties of pure PNIPAAm , SA / PNIPAAm semi‐ IPN , and Ca‐alginate/ PNIPAAm full‐ IPN hydrogels were investigated. The formation of semi‐ IPN and full‐ IPN significantly improved the hydrogels’ swelling capability and mechanical properties without altering their thermosensitivity. 5‐Fluorouracil (5‐Fu) was selected as a model drug to study the release behaviors of the hydrogels. It was found that in vitro controlled drug release from semi‐ IPN hydrogels showed an initial release burst, followed by a slower and sustained release, before reaching equilibrium. Full‐ IPN hydrogels showed slow and sustained release during the whole process. Temperature and pH were found to affect the rate of drug release. Ca‐alginate/ PNIPAAm full‐ IPN hydrogels have potential application as drug delivery matrices in controlled drug release.