pH sensitive Laponite/alginate hybrid hydrogels: swelling behaviour and release mechanism

Alginate hydrogels containing biocompatible Laponite (LP) were prepared and dried under vacuum or in an oven, and their drug release properties at different pH values were studied in vitro using methylene blue (MB) as a model of a cationic drug. These hybrid hydrogels showed a greater encapsulation efficiency of MB, a better sustained release and higher pH sensitivity in MB release, compared to the pure AG gels. The oven-dried hybrid gels were more pH sensitive in MB release than the vacuum-dried ones. Furthermore, the presence of LP, the drying mode and the pH value were shown to influence the mechanism of MB release. LP/AG hybrid gels are, thus, good candidates for the controlled delivery of cationic drugs under acidic conditions.