Department of Chemistry , The Chinese University of Hong Kong , Shatin , N.T., Hong Kong SAR, PR China.
College of Chemistry Environmental Engineering , Shenzhen University , Shenzhen , Guangdong 518060 , PR China.
Langmuir. 2018 Jul 31;34(30):8798-8806. doi: 10.1021/acs.langmuir.8b01968. Epub 2018 Jul 23.
Hydrophilic or zwitterionic polymer-functionalized surfaces have become attractive biomaterials in bioscience and technology due to their excellent protein-resistant ability. Understanding the fundamental interactions between proteins and polymers plays an essential role in the surface design of biomaterials. In this work, we studied the interactions between bovine serum albumin (BSA) and two sorts of polymer brushes including zwitterionic poly(carboxybetaine methacrylate) (PCBMA) and hydrophilic poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA) in NaCl aqueous solutions directly with a self-established total internal reflection microscope (TIRM) to provide a better understanding of the underlying nonfouling mechanism of polymers. Our results indicate that both the surface charge and brushes length can affect protein adsorption through electrostatic and steric repulsions, respectively. Both PCBMA- and POEGMA-coated surfaces display negative charge properties due to incomplete coverage and ionic adsorption. As a result, strong electrostatic repulsions between proteins and negatively charged polymer-coated surfaces could contribute to the resistance of protein-coated particles in solutions with low ionic strength (0.1, 0.5, and 1 mM) and disappear in solutions with high ionic strength (10 mM). The measured interaction profiles demonstrate that PCBMA brushes could provide apparent steric forces only at high ionic strength (10 mM), where zwitterionic brushes exhibit a relatively extended conformation with a lack of electrostatic forces between intra- and interpolymers. In contrast, the steric repulsion between proteins and POEGMA brushes appears when particles diffuse at low positions in all salt concentrations (0.1-10 mM) with similar steric decay lengths, which results from the unresponsiveness of POEGMA brushes to the salt stimulus.
由于其出色的抗蛋白能力，亲水性或两性离子聚合物功能化表面已成为生物科学和技术中极具吸引力的生物材料。了解蛋白质与聚合物之间的基本相互作用对于生物材料表面设计至关重要。在这项工作中，我们使用自行建立的全内反射显微镜（TIRM）直接研究了牛血清白蛋白（BSA）与两种聚合物刷（包括两性离子聚（羧基甜菜碱甲基丙烯酸酯）（PCBMA）和亲水性聚[寡（聚乙二醇）甲基醚甲基丙烯酸酯]（POEGMA））在 NaCl 水溶液中的相互作用，以便更好地了解聚合物的潜在非粘性机制。我们的结果表明，表面电荷和刷长都可以通过静电和空间排斥分别影响蛋白质吸附。由于不完全覆盖和离子吸附，PCBMA 和 POEGMA 涂层表面均具有负电荷特性。因此，蛋白质和带负电荷的聚合物涂层表面之间的强静电排斥可以有助于抵抗低离子强度（0.1、0.5 和 1 mM）溶液中带涂层蛋白质的颗粒，而在高离子强度（10 mM）溶液中则消失。测量的相互作用曲线表明，仅在高离子强度（10 mM）下，PCBMA 刷才能提供明显的空间力，此时两性离子刷表现出相对伸展的构象，聚合物内和聚合物间缺乏静电力。相比之下，在所有盐浓度（0.1-10 mM）下，当颗粒在低位置扩散时，蛋白质与 POEGMA 刷之间的空间排斥就会出现，并且具有相似的空间衰减长度，这是由于 POEGMA 刷对盐刺激无响应所致。
