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A series of cross-linked gels of Poly(N-isopropylacrylamide) [P(NIPAAm)] and Poly(methacr-ylic acid)[P(MAA)] homopolymers and P(NIPAAm-co-MAA) random copolymers were synthesized based on NIPAAm and MAA using 4,4-Bis-(methacryloylamino) azobenzene (BMAAB) as a cross-linker. The swelling behavior of these hydrogels in different pH buffer solutions was studied. The influential factors of the gels including composition of NIPAAm and MAA, pH and temperature upon swelling behavior were investigated. The obtained gels not only hold pH and thermometrical sensitivity, but also take on enzymatic sensitivity due to the cross-linker could be degraded by enzymes of colon. Swelling equilibrium degree of copolymers was very low in acidic medium, which could avoid drug releasing due to biggish swelling of carrier in stomach. Hydrogels would partly swell owing to higher pH value in small intestine. When arrived in colon, hydrogels completely swelled, meanwhile, azoenzymes located would degrade azo-bonds of polymeric network and then drug released in colon.
A series of cross-linked gels of Poly (N-isopropylacrylamide) [P (NIPAAm)] and Poly (methacr-ylic acid) [P (MAA)] homopolymers and P (NIPAAm-co-MAA) The swelling behavior of these hydrogels in different pH buffer solutions was studied. The influential factors of the gels including composition of NIPAAm and MAA, NIPAAm and MAA using 4,4-Bis- (methacryloylamino) azobenzene (BMAAB) as a cross-linker. pH and temperature upon swelling behavior were investigated. The obtained gels not only hold pH and thermometrical sensitivity, but also take on enzymatic sensitivity due to the cross-linker could be degraded by enzymes of colon. Swelling equilibrium degree of copolymers was very low in acidic When arrived in colon, hydrogels completely swelled, meanwhile, azoenzymes located would degrade azo-bond s of polymeric network and then drug released in colon.