| 초록 |
Environmentally sensitive hydrogels have enormous potential in various applications. Some environmental variables, such as low pH and elevated temperatures, are found in the body. For this reason, pH-sensitive biocompatible and biodegradable hydrogels can be used for site-specific controlled drug delivery. In this study, hydrogels were synthesized by free radical copolymerization with poly(methacrylate)-g-histidine macromers. Since the pKa of the imidazole group of histidine is around 6.5, both the charged and uncharged forms of histidine are present at neutral pH, and their concentration ratio is very sensitive to changes in pH under physiological conditions. These macromers, synthesized by combination with methacryloyl chloride and poly(L-histidine). Poly(ethyleneglycol) dimethacrylate were used as a crosslinking agent and azobisisobutyronitrile (AIBN) was used for initiator. The degree of crosslinking and degree of hydrophilicity were controlled by varying the relative concentration of macromer and crosslinking agent. These hydrogels obtained were characterized by FT-IR, NMR, and SEM. Since pKa value of the macromer was 6.5, the hydrogels swelled below pH 6.5. This is because protonation of histidine residue converts the hydrophobic block into hydrophilic one at lower pH. The results indicate that these histidine grafted hydrogels prepared in this study could be useful for localized delivery of drugs.
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