Gamma Radiation-Assisted Synthesis of Xanthan Gum/Acrylamide Hydrogels for Drug Delivery

Xanthan gum (XG) and acrylamide (AAm) hydrogels were synthesized using gamma radiation. The novelty lies in the use of a simple methodology to obtain two different architectures, thereby tailoring their physicochemical properties. The first system is a comb-type hydrogel (net-AAm)-g-XG, where the crosslinking of AAm and the XG grafting were carried out in a single step via gamma radiation. The second system consists of an interpenetrating network (IPN) (net-XG)-inter-(net-AAm), where XG was crosslinked with citric acid and then AAm was crosslinked by gamma radiation in the presence of XG gel. Good degrees of grafting (60%) and interpenetration (75%) were obtained at 8 kGy for both systems. Comb-type and IPN hydrogels showed a porous structure, but the pore size was smaller in the interpenetrating network because this architecture has less internal space due to the presence of a second network. Morphological differences affected water absorption and drug loading/release properties. The comb-type showed its maximum swelling (900%) at 24 h, regardless of the grafting amount; while the IPN exhibited a swelling of 400–600% at 3 h, depending on the interpenetration degree. Both systems allowed for ciprofloxacin loading, but release was faster in the IPN (100 min) than in the comb-type hydrogel (300 min).