Institute of Condensed Matter and Nanosciences, Université catholique de Louvain, Croix du Sud 1 (L7.04.01), 1348 Louvain-la-Neuve, Belgium.
Biomacromolecules. 2013 Jan 14;14(1):215-25. doi: 10.1021/bm301637h. Epub 2012 Dec 27.
Adsorption of proteins at interfaces is an ubiquitous phenomenon of prime importance. Layers of poly(ethylene oxide) (PEO) are widely used to repel proteins. Conversely, proteins were shown to adsorb deeply into brushes of poly(acrylic acid) (PAA), and their subsequent partial release could be triggered by a change of pH and/or ionic strength (I). Mixed brushes of these polymers are thus promising candidates to tune protein adsorption onto new smart surfaces. In this work, the synthesis of such mixed brushes was performed based on a "grafting to" approach, the two polymers being either grafted sequentially or simultaneously. Detailed characterization of the obtained brushes using static water contact angle measurements, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy, and polarization-modulation reflection-absorption infrared spectroscopy is presented. While sequential grafting of the two polymers for different reactions times did not give rise to a broad range of composition of mixed brushes, simultaneous grafting of the polymers from solutions with different compositions allows for the synthesis of a range of mixed brushes (mass fraction of PEO in the mixed brushes from 0.35 to 0.65). A key example is then chosen to illustrate the switchable behavior of a selected mixed PEO/PAA brush toward albumin adsorption. The adsorption behavior was monitored with a quartz crystal microbalance. The mixed brush could adsorb high amounts of albumin, but 86% of the adsorbed protein could then be desorbed upon pH and I change. The obtained properties are thus a combination of the ones of PEO and PAA, and a highly switchable behavior is observed toward protein adsorption.
蛋白质在界面处的吸附是一种普遍存在且极其重要的现象。聚环氧乙烷（PEO）层被广泛用于排斥蛋白质。相反，研究表明蛋白质会深度吸附到聚丙烯酸（PAA）刷中，并且通过改变 pH 值和/或离子强度（I）可以触发其部分释放。因此，这些聚合物的混合刷是调节蛋白质在新智能表面上吸附的有前途的候选物。在这项工作中，基于“接枝到”方法合成了这种混合刷，两种聚合物可以顺序或同时接枝。使用静态水接触角测量、X 射线光电子能谱、电化学阻抗谱和偏振调制反射吸收红外光谱对获得的刷进行了详细表征。虽然两种聚合物的顺序接枝进行不同的反应时间不会导致混合刷的组成范围很广，但聚合物从不同组成的溶液中同时接枝可以合成一系列混合刷（混合刷中 PEO 的质量分数从 0.35 到 0.65）。然后选择一个关键示例来说明所选的 PEO/PAA 混合刷对白蛋白吸附的可切换行为。通过石英晶体微天平监测吸附行为。混合刷可以吸附大量的白蛋白，但在 pH 值和 I 值发生变化后，86%的吸附蛋白可以被洗脱。因此，所获得的性质是 PEO 和 PAA 的性质的组合，并且在蛋白质吸附方面表现出高度可切换的行为。
