Protein framework for manipulating nanoparticles and enzymes: from capsules to arrays

宾夕法尼亚大学的Ivan J.Dmochowski教授和Jeffery G.Saven教授得到了化学系大分子、超分子和纳米化学计划的支持，以阐明中空和笼状蛋白质如何形成纳米容器来包裹纳米颗粒和其他蛋白质，如酶。实验方法和理论方法相结合，以了解这些分子系统，并为特定货物和应用设计分子容器。该项目的一个重要目标是开发将单个容器连接在一起以形成三维微阵列结构的化学和方法。其目标是为催化中的特定应用设计微阵列，并将司法设计的微阵列集成到生物传感器和酶货物输送系统等功能设备中。笼状铁蛋白为研究生物纳米超分子组装提供了一个独特的模型系统，而模块化的分子胶囊到阵列的概念为解决纳米技术和生物技术中的许多材料化学挑战提供了一个通用的平台。将小的纳米结构有序地分层组装成更大的、结构良好的阵列可以提供理想的材料性能、自组装和可加工性。研究生和本科生，包括波多黎各大学的学生，正在通过这项合作研究接受多学科培训。此外，正在开展针对初中生和高中生的实验室和课堂活动。对这些活动进行评估，并准备最佳实践发表在化学教育杂志上。铁蛋白将适当大小和连接的无机纳米颗粒或超级带正电的蛋白质包裹在天然组装中。该研究小组的目标是阐明笼状蛋白，如来自黄曲霉的嗜热铁蛋白(AfFtn)如何包裹各种非生物和生物货物，形成稳定的、分子上精确的纳米容器。计算机蛋白质设计确定了增强铁蛋白胶囊稳定性的氨基酸突变。设计和建模也应用于客体物种，如超级正电荷酶，以探索有效包埋铁蛋白的决定因素。分子模拟提供了铁蛋白-纳米颗粒和铁蛋白-蛋白质相互作用的结构和动力学的洞察力。在计算机设计的指导下，一系列扩大的无机纳米颗粒和酶货物正在被识别和评估。实验方法包括从重组蛋白质的产生和加工到铁蛋白在溶液和固体中组装和包裹的生物物理表征。一个重要的目标是将AfFtn胶囊连接到经过设计和结构确定的附着部位，以形成定义明确的阵列。在几个战略中，包括在三重对称铁蛋白孔处加入二价阳离子结合位点，并随后形成带有双羟基甲酸酯连接体的阵列。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Professors Ivan J. Dmochowski and Jeffery G. Saven of the University of Pennsylvania are supported by the Macromolecular, Supramolecular and Nanochemistry Program of the Division of Chemistry to elucidate how hollow and cage-like proteins can form nano-containers to encapsulate nanoparticles and other proteins such as enzymes. Experimental approaches and theoretical methods are combined to understand these molecular systems and to engineer molecular containers for specific cargos and applications. An important aim of the project is to develop chemistries and methods to link single containers together to form three-dimensional microarray structures. The goal is to engineer microarrays for specific applications in catalysis, and to integrate judicially designed microarrays in functional devices, such as biosensors and enzyme cargo delivery systems. Cage-like ferritin proteins provide a unique model system for studying bio-nano supramolecular assembly, and the modular "molecular capsule-to-array" concept provides a versatile platform for addressing many materials chemistry challenges in nanotechnology and biotechnology. Ordered hierarchical assembly of small nanostructures into larger, well-structured arrays can deliver desirable materials properties, self-assembly, and processability. Graduate and undergraduate students, including students from the University of Puerto Rico, are receiving multidisciplinary training through this collaborative research. In addition, laboratory and classroom activities targeting middle, and high school students are being developed. These activities are subjected to evaluation and best practices are prepared for publication in chemical education journals.Ferritin proteins encapsulate appropriately sized and liganded inorganic nanoparticles or super-positively-charged proteins in native-like assemblies. The research team aims to elucidate how cage-like proteins, such as thermophilic ferritin from A. fulgidus (AfFtn), encapsulate various nonbiological and biological cargo to form stable, molecularly precise nano-containers. Computational protein design identifies amino acid mutations that enhance the stability of ferritin capsules. Design and modeling are also applied to guest species, such as super-positively-charged enzymes, to explore determinants of efficient ferritin encapsulation. Molecular simulations provide insight on the structure and dynamics of ferritin-nanoparticle and ferritin-protein interactions. Guided by computational design, an expanded set of inorganic nanoparticles and enzyme cargos are being identified and assessed. Experimental approaches range from the creation and processing of recombinant proteins to the biophysical characterization of ferritin assembly and encapsulation in solution and in the solid-state. An important goal is to link AfFtn capsules at engineered and structurally well-determined attachment sites to form well-defined arrays. Among several strategies to be pursued is the incorporation of divalent cation binding sites at the three-fold symmetric ferritin pores and subsequent formation of arrays with bis-hydroxamate linkers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.