Casali Institute of Applied Chemistry, Institute of Chemistry, Hebrew University of Jerusalem, Israel.
J Tissue Eng Regen Med. 2011 May;5(5):394-401. doi: 10.1002/term.330. Epub 2010 Oct 8.
The objective of this study was to engineer surfaces comprising covalently bound polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO-PPO-PEO) chains, able to coil and uncoil in aqueous media, as a function of temperature. Thermoresponsive surfaces can be used in diverse areas, such as tissue engineering and 'on-command' drug delivery. The grafting scheme was exemplified using a poly(ethylene terephthalate) (PET) film and started with the exposure of the substrate to plasma of ammonia, whereby amine groups were formed on the film. In the next stage, the amine moieties reacted with the hydroxyterminated thermoresponsive PEO-PPO-PEO triblocks via the hexamethylene diisocyanate (HDI) coupling agent. XPS analysis of the PET film after being exposed to plasma of ammonia revealed substantial amounts of nitrogen, as revealed by the sizeable N1s peak observed at 400.2 eV. A large increase in the C1s ether peak at 286.5 eV was apparent after binding the PEO-PPO-PEO triblocks to the substrate. These findings were confirmed by FTIR spectroscopy and supported by water contact angle measurements. PEO-PPO-PEO triblocks were chain extended by reacting them with HDI, whereby longer polyether urethane chains were formed. The long thermoresponsive chains produced (P-F127) were then tethered to the PET surface, following the procedure used to graft the shorter F127 triblocks. The thermoresponsiveness of the surface was demonstrated by measuring the water contact angle of the P-F127-containing surfaces as a function of temperature.
本研究的目的是构建由共价键结合的聚环氧乙烷-聚环氧丙烷-聚环氧乙烷（PEO-PPO-PEO）链组成的表面，这些表面能够在水介质中随温度发生卷曲和伸展。温敏表面可应用于多个领域，如组织工程和“按需”药物输送。该接枝方案以聚对苯二甲酸乙二醇酯（PET）薄膜为例，首先使基底暴露于氨等离子体中，从而在薄膜上形成氨基。在下一步中，胺基团通过六亚甲基二异氰酸酯（HDI）偶联剂与端羟基的温敏 PEO-PPO-PEO 三嵌段共聚物反应。对暴露于氨等离子体后的 PET 薄膜进行 XPS 分析，发现大量氮元素，这可以从观察到的 400.2 eV 处可观的 N1s 峰看出。在将 PEO-PPO-PEO 三嵌段共聚物键合到基底上后，286.5 eV 处的 C1s 醚峰明显增大。这些发现通过傅里叶变换红外光谱（FTIR）得到证实，并得到水接触角测量的支持。通过与 HDI 反应，PEO-PPO-PEO 三嵌段共聚物发生链延伸，形成更长的聚醚型聚氨酯链。然后，通过使用与接枝较短 F127 三嵌段共聚物相同的方法，将长的温敏链（P-F127）接枝到 PET 表面上。通过测量含有 P-F127 的表面的水接触角随温度的变化，证明了表面的温敏性。
