The pH /temperature dually responsive microgels of interpenetrating polymer network( IPN) structure composed of poly( N-isopropylacrylamide)( PNIPAM) network and poly( acrylic acid)( PAA) network( PNIPAM /PAA IPN micr...The pH /temperature dually responsive microgels of interpenetrating polymer network( IPN) structure composed of poly( N-isopropylacrylamide)( PNIPAM) network and poly( acrylic acid)( PAA) network( PNIPAM /PAA IPN microgels) were synthesized by seed emulsion polymerization. The results obtained by dynamic laser light scattering( DLLS) show that the microgels have good pH /temperature dual sensitivities. The temperature sensitive component and the pH sensitive component inside the microgels have little interference with each other. The rheological properties of the concentrated PNIPAM /PAA IPN microgel dispersions as a function of temperature at pH 4. 0 or 7. 0 were investigated by viscometer,and the results displayed that only at pH 7. 0 the dispersions presented thermoreversible thickening behavior. Then the PNIPAM /PAA fibers were prepared by self-assembly of the PNIPAM /PAA IPN microgels in the ice-crystal templates formed by unidirectional liquid nitrogen freezing method. Field emission scanning electron microscopy( FESEM) images indicate that the PNIPAM /PAA fibers are rounded,randomly orientated and interweaved.展开更多
文摘聚N,N-二甲基丙烯酰胺(PDMAA)水凝胶的孔结构过于致密且不可降解,限制了其在组织工程领域的应用。为解决这些问题,笔者利用半互穿聚合物网络(semi-IPN)技术,在PDMAA网络中加入化香果单宁(TA),设计并合成了一系列新型的TA/PDMAA semi-IPN水凝胶,将"细胞黏附及可降解特性"引入水凝胶体系中。结果表明:加入1 m L TA溶液(质量分数为3%)明显改善了凝胶的孔结构,TA/PDMAA semi-IPN水凝胶表现出连续均匀的多孔结构,孔径分布为37.7~87.1μm。在磷酸盐缓冲液(PBS)中,TA/PDMAA semi-IPN水凝胶可以降解,交联剂的含量可以调控降解速率。胞外毒性分析结果证明了TA/PDMAA semi-IPN水凝胶对COS-7细胞及CHO细胞完全无毒,细胞成活率均高于90%。引入TA显著改善了细胞黏附情况,COS-7细胞及CHO细胞可在TA/PDMAA semi-IPN水凝胶表面较好生长。TA/PDMAA semi-IPN水凝胶表现出较好的生物相容性,具有在组织工程领域应用的潜力。
基金National Natural Science Foundations of China(Nos.51073033,51373030)the Fundamental Research Funds for the Central Universities,China(No.2232014D3-43)
文摘The pH /temperature dually responsive microgels of interpenetrating polymer network( IPN) structure composed of poly( N-isopropylacrylamide)( PNIPAM) network and poly( acrylic acid)( PAA) network( PNIPAM /PAA IPN microgels) were synthesized by seed emulsion polymerization. The results obtained by dynamic laser light scattering( DLLS) show that the microgels have good pH /temperature dual sensitivities. The temperature sensitive component and the pH sensitive component inside the microgels have little interference with each other. The rheological properties of the concentrated PNIPAM /PAA IPN microgel dispersions as a function of temperature at pH 4. 0 or 7. 0 were investigated by viscometer,and the results displayed that only at pH 7. 0 the dispersions presented thermoreversible thickening behavior. Then the PNIPAM /PAA fibers were prepared by self-assembly of the PNIPAM /PAA IPN microgels in the ice-crystal templates formed by unidirectional liquid nitrogen freezing method. Field emission scanning electron microscopy( FESEM) images indicate that the PNIPAM /PAA fibers are rounded,randomly orientated and interweaved.
