ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Wollongong, New South Wales 2522, Australia.
Langmuir. 2012 Jun 5;28(22):8433-45. doi: 10.1021/la300692y. Epub 2012 May 22.
Quartz crystal microbalance with dissipation monitoring (QCM-D) was employed to characterize the adsorption of the model proteins, bovine serum albumin (BSA) and fibronectin (FN), to polypyrrole doped with dextran sulfate (PPy-DS) as a function of DS loading and surface roughness. BSA adsorption was greater on surfaces of increased roughness and was above what could be explained by the increase in surface area alone. Furthermore, the additional mass adsorbed on the rough films was concomitant with an increase in the rigidity of the protein layer. Analysis of the dynamic viscoelastic properties of the protein adlayer reveal BSA adsorption on the rough films occurs in two phases: (1) arrival and initial adsorption of protein to the polymer surface and (2) postadsorption molecular rearrangement to a more dehydrated and compact conformation that facilitates further recruitment of protein to the polymer interface, likely forming a multilayer. In contrast, FN adsorption was independent of surface roughness. However, films prepared from solutions containing the highest concentration of DS (20 mg/mL) demonstrated both an increase in adsorbed mass and adlayer viscoelasticity. This is attributed to the higher DS loading in the conducting polymer film resulting in presentation of a more hydrated molecular structure indicative of a more unfolded and bioactive conformation. Modulating the redox state of the PPy-DS polymers was shown to modify both the adsorbed mass and viscoelastic nature of FN adlayers. An oxidizing potential increased both the total adsorbed mass and the adlayer viscoelasticity. Our findings demonstrate that modification of polymer physicochemical and redox condition alters the nature of protein-polymer interaction, a process that may be exploited to tailor the bioactivity of protein through which interactions with cells and tissues may be controlled.
采用石英晶体微天平（QCM-D），研究了模型蛋白牛血清白蛋白（BSA）和纤维连接蛋白（FN）在聚吡咯掺杂硫酸葡聚糖（PPy-DS）上的吸附，作为 DS 载量和表面粗糙度的函数。BSA 在粗糙度增加的表面上的吸附量更大，并且超过了仅由表面积增加所解释的吸附量。此外，在粗糙薄膜上额外吸附的质量与蛋白质层的刚性增加相对应。对蛋白质吸附层的动态粘弹性分析表明，BSA 在粗糙薄膜上的吸附分为两个阶段：（1）蛋白质到达并初始吸附到聚合物表面；（2）吸附后分子重排为更脱水和更紧凑的构象，这有利于更多蛋白质向聚合物界面的募集，可能形成多层。相比之下，FN 的吸附与表面粗糙度无关。然而，在含有最高 DS 浓度（20 mg/mL）的溶液中制备的薄膜表现出吸附质量和吸附层粘弹性的增加。这归因于导电聚合物膜中 DS 载量的增加，导致呈现出更水合的分子结构，表明更伸展和更具生物活性的构象。对 PPy-DS 聚合物氧化还原状态的调制改变了 FN 吸附层的吸附质量和粘弹性。氧化电势增加了总吸附质量和吸附层粘弹性。我们的研究结果表明，聚合物物理化学和氧化还原条件的改变改变了蛋白质-聚合物相互作用的性质，这一过程可用于通过控制与细胞和组织的相互作用来调整蛋白质的生物活性。
