Synthesis and protein adsorption resistance of PEG-modified poly(N-isopropylacrylamide) core/shell microgels
Synthesis and protein adsorption resistance of PEG-modified poly(N-isopropylacrylamide) core/shell microgels
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DOI：
10.1021/ma021186k
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发表时间：
2002-12-17
期刊：
影响因子：
5.5
通讯作者：
Lyon, LA
中科院分区：
文献类型：
--
作者：
Gan, DJ;Lyon, LA
以聚乙二醇（PEG）单甲醚单甲基丙烯酸酯（PEG-MA）为共聚单体，通过自由基沉淀聚合法制备了聚N-异丙基丙烯酰胺（pNIPAm）接枝聚乙二醇（PEG）纳米粒子。发现粒径分布的宽度随着PEG-MA用量的增加而增加，沿着颗粒的体积相变变宽并向其温度转变。然而，通过将PEG空间定位于使用两阶段沉淀聚合方法制备的核-壳pNIPAm颗粒中的颗粒外围，这些影响被最小化。由于PEG链掺入到颗粒中，观察到颗粒表面上的蛋白质吸附减少，特别是当PEG链位于颗粒壳中时。蛋白质吸附测量还表明，当颗粒在高于转变温度的温度下塌陷时，PEG侧链从颗粒表面向外伸展。PEG链的增加的流动性，大概是由于这种表面延伸，证实了通过变温H-1 NMR研究的核心和核壳颗粒。对于其中PEG链位于颗粒核中的颗粒也观察到这种效应，所述颗粒核然后被pNIPAm壳包围。这些结果表明，PEG接枝物可以穿透pNIPAm壳时，它是在其相分离状态。
Thermoresponsive poly(N-isopropylacrylamide) (pNIPAm) nanoparticles grafted with poly(ethylene glycol) (PEG) chains were prepared via free-radical precipitation polymerization, using PEG monomethyl ether monmethacrylate (PEG-MA) as a comonomer. The breadth of the particle size distributions was found to increase with the amounts of the PEG-MA used, along with a broadening of the volume phase transition of the particles and a transition shift to her temperatures. However, these effects were minimized by spatially localizing the PEG to the particle periphery in core-shell pNIPAm particles prepared using a two-stage precipitation polymerization method. Reduced protein adsorption on the particle surface was observed as a result of incorporation of PEG chains into the particles, especially when the PEG chains were located in tire particle shell. The protein adsorption measurements also suggest that the PEG side chains pray stretch outward from the particle surface as the particles collapse at temperature above the transition temperature. The increased mobility of the PEG chains, presumably due this surface extension, was confirmed by variable temperature H-1 NMR studies for both core and core-shell particles. Such effects are also observed for particles where the PEG chains are localized in the particle core, which as then surrounded by a pNIPAm shell. These results suggest that the PEG grafts can penetrate the pNIPAm shell when it is in its phase-separated state.