NSF Materials World Network: Heterogeneous Nucleation on Nanoporous Substrates

拟议的研究工作将支持国际合作之间的Chayen集团在帝国理工学院，伦敦（IC），专门从事蛋白质结晶和Erlebacher集团在约翰霍普金斯大学，巴尔的摩（JHU），专门从事纳米多孔金属的合成和表面改性。通过结合这些专业化，将有效地进行纳米多孔衬底上的异质晶体成核的基础研究。合作的结构与学生和初级人员的重大交流;最终，JHU团队将开发在溶液相结晶的内部技能，和IC组将学习材料合成技术制造纳米多孔金属和纳米多孔金属复合材料，导致结晶的进步一般。从根本上说，我们提出的研究认为一种新的方法来思考的异质成核的大分子物种。在传统的非均质成核理论中，成核速率由溶剂、基质和核之间的相对界面能控制。在这里，我们将定制衬底，使其不仅将一个均匀的表面暴露于溶液中，而是暴露出三维定向成核位点的统计相关分布。对成核理论进行修正以探索这一想法是所提出的工作的重要组成部分，也是普遍应用该技术所必需的。将使用一种新的基底材料/纳米多孔金对大分子在多孔基底上的成核速率进行详细研究纳米多孔金是一种随机、均匀的中孔材料，其平均孔径可以通过简单的化学方法在3-50 nm之间变化。它的表面也很容易进行化学修饰，所有这些特点使它成为这类研究的唯一完美的材料。这项研究的结果将产生对异相成核基本原理的新理解，并普遍适用于蛋白质和胶体结晶。此外，国际合作将有助于建立成核理论和实验的国际网络，桥接薄膜冶金和溶液相结晶学科。

The proposed research effort will support an international collaboration between the Chayen group at Imperial College, London (IC), specializing in protein crystallization and the Erlebacher group at Johns Hopkins University, Baltimore (JHU), which specializes in the synthesis and surface modification of nanoporous metals. By marrying these specializations, a fundamental study of heterogeneous crystal nucleation on nanoporous substrates will be efficiently pursued. The collaboration is structured with significant exchange of students and junior personnel; ultimately, the JHU team will develop in-house skills in solution-phase crystallization, and the IC group will learn materials synthesis techniques for fabricating nanoporous metals and nanoporous metal composites, leading to advances in crystallization generally. Fundamentally, our proposed research considers a new approach to thinking about the heterogeneous nucleation of macromolecular species. In traditional heterogeneous nucleation theory, nucleation rates are controlled by the relative interfacial energies between the solvent, substrate, and nucleus. Here, we will tailor the substrate to expose not just one uniform surface to the solution, but instead to expose a statistically relevant distribution of three-dimensionally oriented nucleation sites. Modifications of nucleation theory to explore this idea is an important part of the proposed work and is required for applying the technique generally.A detailed study of the nucleation rate of macromolecules over porous substrates will be performed using a new substrate material / nanoporous gold Nanoporous gold is a random, uniform, mesoporous material whose mean pore size can be varied from 3-50 nm using simple chemistry. Its surface is also easily chemically modified, and all these features together make it uniquely perfect for this kind of study.The results of this research will yield new understanding of the fundamentals of heterogeneous nucleation, with general applicability to protein and colloidal crystallization. Furthermore, the international collaboration will help to build international networks in nucleation theory and experiment, bridging the disciplines of thin film metallurgy and solution phase crystallization.