Vitamin B12 Controlled Release with Crosslinked Poly (Acrylic Acid) and Poly (Methacrylic Acid) Based on Chitosan and Starch as pH Sensitive Hydrogels

Background: Hydrogels, due to their unique potentials such as high-water content and hydrophilicity are interest for the controlled release of drug molecules. But most of hydrogels are not biodegradable. Method: To address these issues, we have developed hydrogels that combined sensitive polymers such as poly (acrylic acid) and polymethacrylic acid based on Starch and Chitosan. Owing to their unique potentials through combining the characteristics of a hydrogel system (e.g. hydrophilicity and extremely high water content) with a Starch and Chitosan (e.g. biocompatibility and biodegradability, bioadhesiveness and continued drug release properties that can be easily removed from the body that improve sustained drug release systems). Thus, Chitosan-poly(acrylic acid) (CTS-p(AA)), Starchpoly( acrylic acid) (St-p(AA)), and St-Poly(methacrylic acid) (St-p(MAA)), hydrogels were synthesized by radical polymerization method. The effect of pH on the swelling behavior of the hydrogels was also studied. The swelling ratio was measured for all the hydrogel structures, in different media (pH=1.1, 4, 7.4 and 10) as a function of time. Vitamin B12 was loaded into polymeric matrix. Results and Conclusion: The hydrogels loaded with vitamin B12 demonstrated a decrease of release rate in pH = 1.1 compared to pH = 10. Moreover, we investigated the effect of scaffold materials in hydrogels and monomer in dug release in constant pHs. Our results indicated that the release rate of vitamin B12 is in the following order: St-p(AA) > St-p(MAA) >> CTSp(AA).