School of Chemical Engineering, Sichuan University , Chengdu, Sichuan 610065, P. R. China.
ACS Appl Mater Interfaces. 2014;6(21):19405-15. doi: 10.1021/am505506v. Epub 2014 Oct 30.
A novel type of smart microspheres with K(+)-induced shrinking and aggregating properties is designed and developed on the basis of a K(+)-recognition host-guest system. The microspheres are composed of cross-linked poly(N-isopropylacrylamide-co-acryloylamidobenzo-15-crown-5) (P(NIPAM-co-AAB15C5)) networks. Due to the formation of stable 2:1 "sandwich-type" host-guest complexes between 15-crown-5 units and K(+) ions, the P(NIPAM-co-AAB15C5) microspheres significantly exhibit isothermally and synchronously K(+)-induced shrinking and aggregating properties at a low K(+) concentration, while other cations (e.g., Na(+), H(+), NH4(+), Mg(2+), or Ca(2+)) cannot trigger such response behaviors. Effects of chemical compositions of microspheres on the K(+)-induced shrinking and aggregating behaviors are investigated systematically. The K(+)-induced aggregating sensitivity of the P(NIPAM-co-AAB15C5) microspheres can be enhanced by increasing the content of crown ether units in the polymeric networks; however, it is nearly not influenced by varying the monomer and cross-linker concentrations in the microsphere preparation. State diagrams of the dispersed-to-aggregated transformation of P(NIPAM-co-AAB15C5) microspheres in aqueous solutions as a function of temperature and K(+) concentration are constructed, which provide valuable information for tuning the dispersed/aggregated states of microspheres by varying environmental K(+) concentration and temperature. The microspheres with synchronously K(+)-induced shrinking and aggregating properties proposed in this study provide a brand-new model for designing novel targeted drug delivery systems.
基于 K(+)识别主客体体系，设计并开发了一种具有 K(+)诱导收缩和聚集性能的新型智能微球。微球由交联的聚（N-异丙基丙烯酰胺-co-丙烯酰氨基苯并-15-冠-5）（P（NIPAM-co-AAB15C5））网络组成。由于 15-冠-5 单元与 K(+) 离子之间形成稳定的 2:1“夹心型”主客体配合物，P（NIPAM-co-AAB15C5）微球在低 K(+) 浓度下表现出等温同步的 K(+) 诱导收缩和聚集性质，而其他阳离子（例如 Na(+)、H(+)、NH4(+)、Mg(2+)或 Ca(2+)）则不能触发这种响应行为。系统研究了微球的化学成分对 K(+)诱导收缩和聚集行为的影响。通过增加聚合物网络中冠醚单元的含量，可以增强 P（NIPAM-co-AAB15C5）微球对 K(+)诱导聚集的敏感性；然而，改变微球制备中单体和交联剂的浓度对其影响很小。构建了 P（NIPAM-co-AAB15C5）微球在水溶液中分散-聚集转变的状态图作为温度和 K(+)浓度的函数，这为通过改变环境 K(+)浓度和温度来调节微球的分散/聚集状态提供了有价值的信息。本研究中提出的具有同步 K(+)诱导收缩和聚集性能的微球为设计新型靶向药物输送系统提供了全新的模型。
