Yang Zhu, Xie Jianda, Zhou Wei, Shi Wenfang
Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
J Biomed Mater Res A. 2009 Jun 15;89(4):988-1000. doi: 10.1002/jbm.a.31881.
The star-shaped amphiphilic block copolymer (DPEA-PCL-PNIPAAms) with different PCL block lengths was prepared through ring opening polymerization of epsilon-caprolactone (CL) initiated by hydroxyl end-capped dendritic poly(ether-amide) (DPEA-OH), and then coupling with carboxyl end-capped linear poly(N-isopropylacrylamide) (PNIPAAm-COOH) via an esterification process. The molecular structure was characterized by FT-IR, (1)H NMR, and GPC analysis. As the copolymer dissolved in water, the core-shell structural nanoparticle was formed as a micelle. The fluorescence, (1)H NMR, and dynamic light scattering (DLS) techniques were utilized to confirm the formation of micelles. The optical transmittance and US-DSC measurements demonstrated that the micelles performed the reversible dispersion/aggregation behavior in response to temperature through the outer PNIPAAm polymer shell. The micelles loaded with daidzein showed a very rapid drug release speed at temperatures above the lower critical solution temperature (LCST) due to the temperature-induced structural change of the polymeric micelles.
通过以羟基封端的树枝状聚（醚 - 酰胺）（DPEA - OH）引发的ε - 己内酯（CL）开环聚合反应制备了具有不同聚己内酯（PCL）嵌段长度的星形两亲性嵌段共聚物（DPEA - PCL - PNIPAAm），然后通过酯化过程与羧基封端的线性聚（N - 异丙基丙烯酰胺）（PNIPAAm - COOH）偶联。通过傅里叶变换红外光谱（FT - IR）、核磁共振氢谱（¹H NMR）和凝胶渗透色谱（GPC）分析对分子结构进行了表征。当共聚物溶解于水中时，形成了核壳结构的纳米粒子即胶束。利用荧光、¹H NMR和动态光散射（DLS）技术证实了胶束的形成。光学透过率和超声差示扫描量热法（US - DSC）测量表明，胶束通过外部的PNIPAAm聚合物壳表现出响应温度的可逆分散/聚集行为。负载大豆苷元的胶束在温度高于最低临界溶液温度（LCST）时，由于聚合物胶束的温度诱导结构变化，显示出非常快的药物释放速度。
