温敏/pH敏共聚物瓜耳胶-异丙基丙烯酰氨的制备及其水凝胶性质研究

Preparation and characteristics of thermo-and pH-sensitive hydrogel graft of ploy-(iV-isopropylacrylamide)with Guar gum

目的:合成了新型温敏/pH敏感型高分子材料异丙基丙烯酰氨-g-瓜耳胶(PNIAAm-g-GG),并对其性质进行研究。方法:采用链引发法制备了异丙基丙烯酰氨-g-瓜耳胶共聚物,以戊二醛为交联剂制备了聚合物凝胶及其温敏游离膜,并用红外光谱与热重分析对聚合物结构进行确证;采用黏度法测定了聚合物的低温溶解温度(lower critical solution temperature,LCST);考察了离子强度对聚合物LCST的影响,温度对温敏膜药物透过性的影响,同时考察了温度、离子强度及pH值对聚合物凝胶释药的影响。结果:聚合物的LCST为37.5℃,且随溶液中离子强度的增高而线性降低;当温度高于聚合物LCST时,凝胶中药物释放速率减慢,药物经膜的透过性增加;凝胶释药速率随溶出介质中离子强度的增高而降低,随介质pH值降低而加快。结论:异丙基丙烯酰氨-g-瓜耳胶凝胶骨架片具有明显的温度敏感性及pH敏感性。

Objective:To prepare and characterize the thermo-and pH-sensitive hydrogel graft of ploy-(N-isopropylacrylamide) with natural g-Guar gum. Methods: Following poly (N-isopropylacrylamide)-g-Guar gum (PNIAAm-g-GG) was synthesized in a chain reaction, the PNIAAm-g-GG hydrogel and its thermo-sensitive film were prepared by crosslinking with glutaraldehyde (GA). The polymer structure was confirmed by the Fourier transform infrared spectra (FTIR) and thermogravity analysis (TGA).The lower critical solution temperature (LCST) was measured by viscometry. Effect of ion strength on the LCST, and effect of temperature, pH and ion strength on the drug release from the PNIAAm-g-GG hydrogel were investigated. Results: The LCST of PNIAAm-g-GG was about 37. 5℃ and showed a negative correlation with the ion strength. The drug release rate from the hydrogel became slow down when the environmental temperature exceeded the LCST. Dramatically the drug release rate was also influenced with pH, it was faster at lower pH than that at higher pH. Conclusion: The hydrogel of N-isopropylacrylamide-g-Guar gum was thermo-and pH-sensitive as well as ion strength sensitive.