Preparation and Swelling Behavior of Carrageenan-graft-polymethacrylamide Superabsorbent Hydrogel as a Releasing Drug System

The polysaccharide, kappa-carrageenan (κC) was chemically modified to achieve a novel superabsorbent hydrogel via graft copolymerization of acrylamide (AAm) onto the substrate followed by alkaline hydrolysis. Ammonium persulfate (APS) and N,N'-methylene bisacrylamide (MBA) were used as a free-radical initiator and a crosslinker, respectively. The saponification reaction was carried out using sodium hydroxide aqueous solution. Either κC-g-PAAm or hydrolyzed κC-g-PAcA was characterized by FTIR spectroscopy. The effect of media variables such as alkaline hydrolysis conditions (i.e., NaOH concentration, hydrolysis time and temperature) were systematically optimized to achieve a hydrogel with swelling capacity as high as possible. Absorbency of superabsorbing hydrogels was examined in buffer solutions with pH ranged 1-13. Also, the pH reversibility and on-off switching behavior, at pH 2.0 and 9.0, makes the synthesized hydrogels as a good candidate for controlled delivery of bioactive agents. Finally, the κC-g-PAcA hydrogel exhibited a pH-responsiveness character so that a swelling-deswelling pulsatile behavior was recorded at pH 1.2 and 7.4. In addition, the delivery behavior of Acetaminophen from the hydrogel bead was studied.