¹Department of Chemistry, Science Faculty, Islamic Azad University,Arak Branch, Arak Iran

²Department of english,Humaniti Faculty,Islamic Azad University,Arak Branch, Arak Iran

Superabsorbent polymers are obtained by the graft copolymerization of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) monomer onto collagen, using ammonium persulfate as a free radical initiator in the presence of methylene bisacrylamide as a crosslinker. The synthesized hydrogels were subjected to equilibrium swelling studies in simulated gastric and intestinal fluids (SGF and SIF). So, we investigated the pH-sensitivity of the hydrogel. Ionic repulsion between charged groups incorporated in the gel matrix by an external pH modulation could be assumed as the main driving force responsible for such abrupt swelling changes, because this superabsorbent network intelligently responding to pH can be considered as an excellent way to design novel drug delivery systems, Therefore, we investigated the release behavior of B₁₂ from this kind of responsive hydrogel. The concentration of released B₁₂ was monitored at 370nm on the UV spectrophotometer. The release value of drug from hydrogels at pH 7.4 was higher than that at pH 1.6 due to the electrostatic repulsion between sulfonate groups and the higher swelling capacity of the hydrogel.