pH敏感瓜胶/聚丙烯酸半互穿网络水凝胶研究

制备了瓜胶/聚丙烯酸(GG/PAA)的半互穿网络(sem i-IPN)水凝胶,以N,N-亚甲基双丙烯酰胺(MBA)为交联剂,考察了加料量、溶胀介质pH对平衡溶胀率(ESR)的影响。结果表明:GG/PAA半互穿网络水凝胶的ESR在pH≤3时较小,pH>4后增加较快,pH=8.2时达最大值,继续增加pH,ESR又呈下降趋势,体系具有pH敏感性。在pH相同条件下,ESR随GG用量增加而减小,随丙烯酸(AA)用量增加而增大。pH=8.2、ρ(GG)从5 g/L增加到25 g/L时,ESR从3 142降低到1 026;当ρ(AA)用量从125 g/L增加到375 g/L时,ESR从1 195增加到2 611。m(MBA)∶m(AA)=(0.5∶100)~(1.2∶100)时,ESR略有增加。GG/PAA半互穿网络水凝胶的溶胀动力学表明,该类凝胶满足在胃液pH环境中溶胀率较小、小肠部位pH环境中溶胀率较高的要求,因此,通过调整配方,结合瓜胶只被结肠部位细菌降解的特性,GG/PAA半互穿网络水凝胶有望成为一种理想的靶向结肠给药载体。

Study of pH-Sensitive GG/PAA Semi-interpenetrating Polymer Network

A process was developed to prepare pH-sensitive guar gum/poly (acrylic acid) (GG/PAA) hydrogels using N,N-methylenebisacrylamide as cross-linker with a semi-interpenetrating polymer network (semi-IPN) structure by free radical solution polymerization.Influence of feed composition and pH of the swelling medium on the equilibrium swelling ratio (ESR) was investigated.Results show that ESR of GG/PAA semi-IPN hydrogels with various feed composition is dependent on the pH of the swelling medium.At pH≤3.0,ESR is very low and shows little change with pH,but increases sharply with pH value in the range of 4.0~8.2,and goes to its maximum at pH 8.2 and then decreases with the increase of pH.In pH 8.2 buffer,ESR decreases from (3 142) to (1 026) when the amount of guar gum increases from 5 to 25 g/L in the composition,but increases from (1 195) to (2 611) with the increase of acrylic acid amount from 125 to 375 g/L.ESR increases slightly with the cross-linker amount changing from 0.5% to 1.2%(wt%) based on acrylic acid charged weight .The kinetic dynamics in buffers with the pH close to simulated gastric liquid and intestine liquid shows that the swelling ratio of the GG/PAA semi-IPN hydrogel (GA5) is higher in the latter than in the former.Thus,pH sensitivity and colonic-specific degradability of GG component could make GG/PAA semi-IPN hydrogels good candidates for colon-specific drug delivery carriers.