Building colloidal assemblies via site-specific bonding regions

美国国家科学基金会-化学与运输系统分部-颗粒与多相过程项目（1415）提案编号：0651611主要研究人员：Velegol， darrel隶属机构：宾夕法尼亚州立大学-大学公园提案标题：通过特定位点的键合区域构建胶体组件胶体和纳米胶体历史上一直用于单一目的，例如聚合物胶体形成薄膜或TiO2颗粒散射光。近年来，已经形成了更复杂的颗粒，可以进行受控的药物输送或成像。未来的需求将需要更复杂、多用途的组件。这些组件可能具有修复、传感或控制释放等核心功能，但也可以通过磁性或荧光成像来移动。存在各种组装复杂粒子的方法；然而，这些方法还没有提供一种通用的、可扩展的方法来组装各种材料、尺寸和化学功能的颗粒。在这个建议中，化学和物理方法都被提出，通过在单个粒子上放置特定位点的键合区域来构建复杂的组装体。化学上，“颗粒光刻”方法可以将分子或纳米胶体特定位置放置在更大的胶体颗粒（100纳米大小）上。在用适当的化学物质对胶体颗粒进行定型后，它可以很容易地组装到其他颗粒上。物理上，通过在特定位置使颗粒略微变平而获得的局部耗竭力使胶体颗粒能够以易于调节的键合强度结合。愿景是，特定位置的功能化将使制造胶体装置在许多应用领域。例如，药物递送组件可能包括具有用于成像的荧光颗粒的水凝胶颗粒和用于靶向的抗原包被颗粒；环境修复组件可能包括用于污染物吸收的聚合物胶体和用于运输的磁性胶体；机器人装置可能由用于检测的传感器粒子和用于运输的电动纳米马达组成。组装这些和其他设备的一个关键瓶颈是理解组装过程的基本化学和物理。这项工作的智力优点是开发了用于组装胶体颗粒的可控的、特定位点的键合方法。用分子来类比，我们建议制造具有“键价”的“胶体原子”，使它们能够自组装成“胶体分子”。颗粒光刻方法允许局部化学功能化，而局部耗竭力允许可旋转和可调谐的键合。发展这些方法要求我们提高胶体物理学的基本知识，特别是在粒子间力方面。更广泛的影响这项工作的更广泛的影响集中在将博士生的研究整合到与高中生的长期互动中。我的博士生学习实验（例如，电泳，FESEM，合成）和建模（例如，布朗动力学，胶体力）技术，我们与高度参与的宾夕法尼亚州中部艺术节合作，向1000多名K-3学生和他们的父母展示有趣的科学。经过两年的短期互动，我们现在假设与秃鹰地区高中物理系学生长达一年的互动将对物理考试成绩和学生进入科学和工程职业产生重大影响。我们将通过合作来检验这一假设。博士生也将他们的研究与REU的培训相结合；在我的实验室里，过去有六名REU学生和博士生一起发表了他们的作品。我们的研究将发表在Langmuir， Nano Letters和Advanced Materials等期刊上，使其广泛曝光。

National Science Foundation - Division of Chemical &Transport Systems Particulate & Multiphase Processes Program (1415)Proposal Number: 0651611Principal Investigators: Velegol, DarrellAffiliation: Pennsylvania State University - University ParkProposal Title: Building colloidal assemblies via site-specific bonding regionsIntellectual MeritColloids and nanocolloids have historically been used for single purposes, such as polymer colloids forming films or TiO2 particles scattering light. In recent years more complex particles have been formed that can perform controlled drug delivery or imaging. Future demands will require even more complex, multi-purpose assemblies. Such assemblies might have a central function like remediation, sensing, or controlled release, but could also be moved magnetically or imaged fluorescently. Various methods exist for assembling complex particles; however, these methods have not provided a general and scalable way to assemble particles of various materials, sizes, and chemical functionalities.In this proposal both chemical and physical approaches are proposed for building complex assemblies by placement of site-specific bonding regions on individual particles. Chemically, the "particle lithography" method enables the site-specific placement of molecules or nanocolloids onto larger colloidal particles (100 nm in size). After a colloidal particle is patterned with the appropriate chemistry, it can be assembled readily to other particles. Physically, localized depletion forces obtained by slightly flattening particles at specified locations enable colloidal particles to be bonded with an easily-tunable bond strength. The vision is that site-specific functionalization will enable fabrication of colloidal devices in many fields of application. For example, drug delivery assemblies might consist of hydrogel particles with fluorescent particles for imaging and antigen-coated particles for targeting; environmental remediation assemblies might consist of polymer colloids for contaminant absorption and magnetic colloids for transport; robotic devices might consist of sensor particles for detection and electrokinetic nanomotors for transport. A key bottleneck to assembling these and other devices is understanding the fundamental chemistry and physics of the assembly processes.The intellectual merit of this work is the development of controlled, site-specific bonding methods for assembling colloidal particles. To use a molecular analogy, we propose to make "colloidal atoms" having "bonding valences" that enable them to self-assemble into "colloidal molecules". The particle lithography method allows local chemical functionalization, while the localized depletion forces allow rotatable and tunable bonding. Developing these methods requires us to advance the knowledge of fundamental colloidal physics, especially in interparticle forces.Broader ImpactThe broader impacts of this work focus on the integration of PhD student research into longer-term interactions with high school students. My PhD students learn both experimental (e.g., electrophoresis, FESEM, synthesis) and modeling (e.g., Brownian dynamics, colloidal forces) techniques, and we have worked with the highly-attended Central Pennsylvania Festival of the Arts to show interesting science to over 1000 K-3 students and their parents. After two years of these short-term interactions, we now hypothesize that year-long interactions with Physics students at Bald Eagle Area High School will have a significant impact on Physics test scores and students entering science and engineering careers. We will test this hypothesis in a collaborative effort. The PhD students also integrate their research with REU training; the past half dozen REU students in my lab have earned their name on published work alongside the PhD students. Our research will be published in journals like Langmuir, Nano Letters, and Advanced Materials, giving it broad exposure.