PECASE: Molecular Design and Nanomechanical Testing of High-Toughness Biomimetic Polymeric Systems

该CAREER提案的研究部分涉及仿生“模块化”聚合物系统的设计和纳米力学测试，该系统在分子水平上具有高度可控的机械性能。 提出了一种改进合成大分子的分子韧性的一般设计策略，该策略涉及合成的“主体”聚合物与较小的、纳米尺寸的、形状持久的“客体”的非特异性、非共价络合。“这项研究将开始，研究一个模型系统，其中涉及充分研究的复合聚（环氧乙烷）（PEO），-[CH 2-CH 2-O]n-和小球状蛋白，人血清白蛋白（HSA）。 一个PEO链端到表面的化学连接和足够低的链接枝密度将使用混合单层技术实现，该混合单层技术涉及单（硫醇）官能化的PEO和自组装的烷醇单分子层（SAM）在金上的共化学吸附。 然后将PEO底物在HSA溶液中孵育以形成表面固定的大分子复合物。 将采用高分辨率力光谱法通过非特异性物理吸附相互作用将单个大分子复合物拴系到探针尖端，并将在水溶液中测量延伸纳米机械特性（例如，力F与分离距离D）。 为了控制分子的弹性和韧性，将研究各种参数，例如主体聚合物分子量、两个相邻客体之间的主体链段的长度、pH和离子强度。 从长远来看，该研究项目将扩大到包括其他一般类别的“客人”，包括树枝状聚合物，SAM功能化纳米颗粒和互补寡聚体覆盖纳米颗粒。本职业计划中描述的教育活动与研究目标紧密结合，将使材料科学专业的学生接触到材料性质和行为的分子起源。 第二个目标是向来自不同学科的学生展示纳米技术领域最新，最令人兴奋的科学发现，并鼓励他们从事本科研究项目，申请研究生院和/或从事研究和学术事业。 这将通过一个新的学期的本科课程题为“材料和生物材料的纳米力学”，在我们的“独立活动期间”题为“纳米技术科学与工程”，为期一周的研究生水平的实验室暑期课程题为“高分辨率力光谱学，“和推广到高中教师。

The research component of this CAREER proposal involves the design and nanomechanical testing of biomimetic, "modular" polymeric systems with highly controlled mechanical properties at the molecular level. A general design strategy for improving the molecular toughness of synthetic macromolecules is proposed which involves the nonspecific, noncovalent complexation of a synthetic "host" polymer with smaller, nanometer-size, shape-persistant "guests." The research will begin by studying a model system which involves the well-studied complexation of poly(ethylene oxide) (PEO), -[CH2-CH2-O]n- and the small globular protein, human serum albumin (HSA). Chemical attachment of one PEO chain end to a surface and sufficiently low chain grafting densities will be achieved using a mixed monolayer technique involving the co-chemisorption of mono(thiol)-functionalized PEO and a self-assembling alkanethiol monolayer (SAM) on gold. The PEO substrates will then be incubated in an HSA solution to form surface-immobilized macromolecular complexes. High-resolution force spectroscopy will be employed to tether the individual macromolecular complexes to a probe tip via nonspecific, physisorption interactions and the extensional nanomechanical properties (e.g. force, F, versus separation distance, D) will be measured in aqueous solution. A variety of parameters will be studied in order to control the molecular elasticity and toughness, such as the host polymer molecular weight, the length of host chain segment between two neighboring guests, pH, and ionic strength. In the long-term, this research project will be expanded to include other general classes of "guests" including dendrimers, SAM-functionalized nanoparticles, and complementary oligomer-clothed nanoparticles.%%%The educational activities described in this CAREER proposal are strongly integrated with the research objectives and will expose materials science students to the molecular origins of material properties and behavior. A secondary goal is to show students from a variety of disciplines some of the latest, most exciting scientific discoveries in the field of nanotechnology and to encourage them to take up undergraduate research projects, apply to graduate school, and / or pursue a career in research and academia. This will be achieved through the continuing development of a new semester-long undergraduate course entitled "Nanomechanics of Materials and Biomaterials," the creation of a special 4-week undergraduate course during our "independent activities period" entitled " Nanotechnology Science and Engineering," the creation of a week-long, graduate-level laboratory summer course entitled " High-Resolution Force Spectroscopy," and outreach to high school teachers.