Protein repellency of well-defined, concentrated poly(2-hydroxyethyl methacrylate) brushes by the size-exclusion effect
Protein repellency of well-defined, concentrated poly(2-hydroxyethyl methacrylate) brushes by the size-exclusion effect
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DOI：
10.1021/ma0520242
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发表时间：
2006-03-21
期刊：
影响因子：
5.5
通讯作者：
Kishida, A
中科院分区：
文献类型：
--
作者：
Yoshikawa, C;Goto, A;Kishida, A
通过石英晶体微天平（QCM）和荧光显微镜系统地研究了聚（甲基丙烯酸2-羟乙酯）（PHEMA）刷上蛋白质的吸附作为接枝密度和蛋白质尺寸的函数。接枝密度a（链/nm(2)）范围为0.007（稀或半稀刷方式）至0.7（浓刷方式），蛋白质尺寸的有效直径范围为2至13 nm。最低密度的刷子（sigma = 0.007）吸附了所有测试的四种蛋白质，而最高密度的刷子（a = 0.7）不吸附任何蛋白质。中等密度的刷子（sigma = 0.06）表现出中间行为，吸附最小的两种蛋白质，但有效地排斥最大的两种蛋白质。 PHEMA流延膜吸附了探针蛋白，吸附量与膜厚度大致成正比增加，表明吸附主要发生在膜的本体中。刷子的上述结果支持尺寸排除效应的想法，这是浓缩聚合物刷的一种效应特征，其中接枝链高度延伸和高度定向，使得与最近邻接枝点之间的距离相比足够大的大分子在物理上被排除在整个刷层之外。在这方面，正如事实上所观察到的，最低密度刷的行为应该基本上类似于流延膜的行为。
The adsorption of proteins on poly(2-hydroxyethyl methacrylate) (PHEMA) brushes was systematically studied by quartz crystal rnicrobalance (QCM) and fluorescence microscopy as a function of graft density and protein size. The graft density a (chains/nm(2)) ranged from 0.007 (dilute or semidilute brush regime) to 0.7 (concentrated brush regime), and the protein size ranged from 2 to 13 nm in an effective diameter. The lowest-density brush (sigma = 0.007) adsorbed all the tested four proteins, while the highest-density brush (a = 0.7) adsorbed none of them. The middle-density brush (sigma = 0.06) showed an intermediate behavior, adsorbing the smallest two proteins but effectively repelling the largest two. PHEMA cast films adsorbed a probe protein with the adsorbed amount increasing approximately proportionally to the film thickness, indicating that the adsorption mainly occurred in the bulk of the film. The noted results for the brushes support the idea of size-exclusion effect, an effect characteristic of concentrated polymer brushes, in which the graft chains are highly extended and highly oriented so that large molecules, sufficiently large compared with the distance between the nearest-neighbor graft points, are physically excluded from the entire brush layer. In this regard, the behavior of the lowest-density brush should be essentially similar to that of the cast film, as was in fact observed.