Protein Interactions with Nano-Scale Controlled Surfaces: The Molecular Basis for Non-fouling Behavior

蛋白质吸附的表面阻力是目前人们非常感兴趣的研究课题，对生物传感器、植入型生物材料和药物载体的性能至关重要。由于蛋白质具有不同的形状和表面功能，蛋白质的吸附强烈依赖于表面的纳米级化学和结构属性。尽管在蛋白质吸附方面进行了广泛的研究，但对其无污染机理仍缺乏分子水平的了解。本文提出的实验和模拟相结合的研究将针对这一重要问题。智力优势：由NSF SGER赠款(1/1/03-3/31/04)支持的PI.s小组最近的模拟和实验研究表明，低聚乙二醇(OEG)自组装单分子膜(SAM)的无污垢特性与OEG链的水化/柔性之间存在关联。然而，目前还缺乏对结合在OEG链上的水分子的含量和结构的实验测量。为了阐明蛋白质表面吸附阻力的分子来源，目前还没有通过分子模拟直接评估蛋白质和OEG表面之间的相互作用力。此外，关于基于OEG或聚乙二醇基(PEG)的材料何时工作或失败，特别是在较高温度下，还有尚未解决的问题。为了在分子水平上对无垢机理有一个完整而坚实的了解，本工作将解决三个重要问题：(A)通过分子模拟获得蛋白质分子接近OEG SAM表面时的力-距离曲线，(B)利用石英晶体微天平(QCM)/表面等离子体共振(SPR)联合实验探索OEG链中结合的水分子的数量和结构，以及(C)利用SPR研究高温下OEG SAM的无垢机理。由于表面的分子细节对蛋白质的吸附非常重要，使用混合的OEG/OH自组装膜或乙醇和水的混合组装溶剂将改变OEG的表面密度和结构。在整个研究过程中，将使用疏水性CH3和亲水性羟基封端的自组装膜作为参照系。这些研究中使用的所有自组装膜都将使用X射线光电子能谱(XPS)和原子力显微镜(AFM)进行充分表征。更广泛的影响：这个为期一年的项目的成功将促进我们在分子水平上对无垢机理的基本理解，为评价无垢材料提供新的标准，并有助于新的无垢材料的设计。它将对从生物传感器到生物材料、药物输送、组织工程到海洋涂料的各种应用产生重大影响。虽然无污垢表面对这些技术至关重要，但对无污垢机理的基础研究是发现新的防污材料和涂层的动力。研究生和本科生将参与这个项目，特别是来自代表性不足群体的学生。本科生研究人员将通过在当地研究中心建立的良好外展计划招募，国际和平研究所一直积极参与其中。这些知识将通过课程传播，例如。纳米技术前沿。材料的计算模拟和建模。

ABSTRACT - 0433753Surface resistance to protein adsorption is currently a subject of great interest and is critical to the performance of biosensors, implanted biomaterials, and drug carriers. Since proteins have distinct shapes and surface functionalities, protein adsorption is strongly dependent on the nano-scale chemical and structural properties of the surface. Despite extensive research in protein adsorption, there is still a lack of a molecular-level understanding of the non-fouling mechanism. Combined experimental and simulation studies proposed in this work will target this important problem. Intellectual Merit: From recent simulation and experimental studies from the PI.s group supported through a NSF SGER grant (1/1/03-3/31/04), it appears that there is a correlation between the non-fouling properties of oligo (ethylene glycol) (OEG) self-assembled monolayers (SAMs) and the hydration/flexibility of OEG chains. However, there is a lack of experimental measurements of the content and structure of water molecules bound in OEG chains. There has been no direct evaluation of the interaction forces between a protein and an OEG surface from molecular simulations in order to elucidate the molecular origin of surface resistance to protein adsorption. Furthermore, there are unresolved issues about when OEG- or poly(ethylene glycol) (PEG)-based materials work or fail, particularly at higher temperatures. In order to provide a complete and solid understanding of the non-fouling mechanism at the molecular level, three important problems will be tackled in this work: (a) to obtain force-versus-distance curves as a protein molecule approaches an OEG SAM surface from molecular simulations, (b) to probe the amount and structure of water molecules bound in OEG chains using combined quartz crystal microbalance (QCM)/surface plasmon resonance (SPR) experiments, and (c) to study the non-fouling mechanism of OEG SAMs at higher temperatures using SPR. Since the molecular details of a surface are of great importance to protein adsorption, OEG surface density and structure will be altered using either mixed OEG/OH SAMs or mixed ethanol and water assembly solvents. Hydrophobic CH3 and hydrophilic OH terminated SAMs will be used throughout these studies as reference systems. All the SAMs used in these studies will be fully characterized using X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Broader Impact: The success of this one year project will advance our fundamental understanding of the non-fouling mechanism at the molecular level, provide new criteria to evaluate non-fouling materials, and assist the design of new non-fouling materials. It will have significant impact on various applications ranging from biosensors to biomaterials, drug delivery, and tissue engineering to marine coatings. While non-fouling surfaces are critical to these technologies, a fundamental study of the non-fouling mechanism is a driving force for discoveries of new anti-fouling materials and coatings. Graduate and undergraduate students will be involved in this project, particularly students from underrepresented groups. Undergraduate researchers will be recruited through well-established outreach programs at local research centers, in which the PI has been actively involved. The knowledge will be disseminated through the courses, such as. Frontiers in Nanotechnology., .Computational Simulation and Modeling of Materials.