Protein-Associated Water and Secondary Structure Effect Removal of Blood Proteins from Metallic Substrates
Protein-Associated Water and Secondary Structure Effect Removal of Blood Proteins from Metallic Substrates
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DOI：
10.1021/la1041794
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发表时间：
2011-03-01
期刊：
影响因子：
3.9
通讯作者：
Belfort, Georges
中科院分区：
文献类型：
--
作者：
Anand, Gaurav;Zhang, Fuming;Belfort, Georges
从金属中去除吸附的蛋白质具有显著的健康和工业后果。有许多蛋白质吸附的研究，使用模型自组装单层或聚合物基板，但几乎没有任何高分辨率的测量吸附和去除蛋白质的工业相关的过渡金属。外科医生和船主希望清洁的金属表面，以减少疾病通过手术器械的传播，并使表面污染最小化（以减少摩擦和腐蚀）。这项工作的一个主要发现是，除了疏水相互作用的粘附能，在吸附的蛋白质层和蛋白质的二级结构中的水含量确定的访问，因此能够从金属表面去除吸附的蛋白质与强碱性表面活性剂溶液（NaOH和5毫克/毫升SDS在PBS中，pH 11）。这用三种血液蛋白（牛血清白蛋白、免疫球蛋白和纤维蛋白原）和四种过渡金属基底和不锈钢（铂（Pt）、金（Au）、钨（W）、钛（Ti）和316级不锈钢（SS））证明。检查所有金属基材的化学污染物，如碳和硫，并使用X射线光电子能谱（XPS）进行表征。而Pt和Au表面是无氧化物的（相当惰性的元素），W，Ti和SS衬底与自然氧化物。石英晶体微天平与耗散（QCM-D）和表面等离子体共振光谱（SPR）之间的差异测量提供了蛋白质吸附层中的水含量的测量。疏水粘附力，获得与原子力显微镜，蛋白质和金属之间的吸附的蛋白质-水复合物的量。因此，吸附的蛋白质的量随着Pt、Au、W、Ti和SS的顺序而减少。无论是固着接触角，也不是金属基板的表面粗糙度是有用的预测在这里。所有三种球状蛋白在添加碱性-表面活性剂清洁溶液时表现相似，其中铂和金表现出增加，而钨、钛和不锈钢显示出重量减少。根据QCM-D的耗散测量，铂和金的吸附层是刚性的，而钨、钛和不锈钢的吸附层则柔性得多。SDS碱性溶液对W、Ti和SS吸附蛋白质的去除率取决于吸附层的含水量，而对Pt和Au则取决于二级结构含量。当蛋白质吸附高（Pt，Au），蛋白质蛋白质相互作用和蛋白质表面相互作用占主导地位，蛋白质层的去除是有限的。当蛋白质吸附量低时，吸附蛋白质层的含水量是碱性SDS如何有效去除该层的决定因素。因此，蛋白质蛋白质和蛋白质表面的相互作用是最小的和蛋白质结构的扰动相比，高蛋白质吸附。二级结构含量决定了高吸附量蛋白质的有效去除。
Removing adsorbed protein from metals has significant health and industrial consequences. There are numerous protein-adsorption studies using model self-assembled monolayers or polymeric substrates but hardly any high-resolution measurements of adsorption and removal of proteins on industrially relevant transition metals. Surgeons and ship owners desire clean metal surfaces to reduce transmission of disease via surgical instruments and minimize surface fouling (to reduce friction and corrosion), respectively. A major finding of this work is that, besides hydrophobic interaction adhesion energy, water content in an adsorbed protein layer and secondary structure of proteins determined the access and hence ability to remove adsorbed proteins from metal surfaces with a strong alkaline-surfactant solution (NaOH and 5 mg/mL SDS in PBS at pH 11). This is demonstrated with three blood proteins (bovine serum albumin, immunoglobulin, and fibrinogen) and four transition metal substrates and stainless steel (platinum (Pt), gold (Au), tungsten (W), titanium (Ti), and 316 grade stainless steel (SS)). All the metallic substrates were checked for chemical contaminations like carbon and sulfur and were characterized using X-ray photoelectron spectroscopy (XPS). While Pt and Au surfaces were oxide-free (fairly inert elements), W, Ti, and SS substrates were associated with native oxide. Difference measurements between a quartz crystal microbalance with dissipation (QCM-D) and surface plasmon resonance spectroscopy (SPR) provided a measure of the water content in the protein-adsorbed layers. Hydrophobic adhesion forces, obtained with atomic force microscopy, between the proteins and the metals correlated with the amount of the adsorbed protein-water complex. Thus, the amount of protein adsorbed decreased with Pt, Au, W, Ti and SS, in this order. Neither sessile contact angle nor surface roughness of the metal substrates was useful as predictors here. All three globular proteins behaved similarly on addition of the alkaline-surfactant cleaning solution, in that platinum and gold exhibited an increase, while tungsten, titanium, and stainless steel showed a decrease in weight. According to dissipation measurements with the QCM-D, the adsorbed layer for platinum and gold was rigid, while that for the tungsten, titanium, and stainless steel was much more flexible. The removal efficiency of adsorbed-protein by alkaline solution of SDS depended on the water content of the adsorbed layers for W, Ti, and SS, while for Pt and Au, it depended on secondary structural content. When protein adsorption was high (Pt, Au), protein protein interactions and protein surface interactions were dominant and the removal of protein layers was limited. Water content of the adsorbed protein layer was the determining factor for how efficiently the layer was removed by alkaline SDS when protein adsorption was low. Hence, protein protein and protein surface interactions were minimal and protein structure was less perturbed in comparison with those for high protein adsorption. Secondary structural content determined the efficient removal of adsorbed protein for high adsorbed amount.