Vectorially-Coupled Reaction Networks in Low-Dimensional Nanofluidic Structures

反应是化学反应的中心事件，控制它们的行为和发生位置是化学测量和制造新化学品的核心。理想情况下，科学家希望设计出快速发生的反应，有效利用所有化学参与者，使用廉价的化学品和环境友好的条件，并生产容易分离的化学产品。在自然界中，例如在生物细胞中，这些严格的目标是通过空间组织的反应网络实现的。圣母大学的保罗·博恩博士的研究团队通过设计和开发反应网络来模拟自然，这些网络的行为由电刺激控制，其位置由反应容器的大小决定。在研究电子转移反应时，他们用纳米材料精心构建了特殊设计的结构，纳米材料的性质和放置导致在特定位置发生特定、明确和高效的反应。此外，对特定位置的反应和附近液体移动的电子控制允许化学产品从一个反应地点穿梭到另一个下游，在那里它们被用作另一个确定的反应过程的化学起始材料。所有的反应都是使用酶来加速的，酶是自然界的化学反应催化剂。博恩团队正在研究如何通过施加电压来控制催化剂的活性。这些研究工作与新的教育和培训项目相结合，这些项目跨越了圣母大学内部的学科界限，并结合了多所大学的人才。在这个过程中，这些活动满足了NSF的具体目标，包括发展一支多样化的、具有全球竞争力的科学-技术-工程-数学劳动力队伍；加强学术界和工业界之间的伙伴关系；以及提高经济竞争力。该项目由化学测量和成像计划以及来自NSF的分子分离、电化学系统和过程系统、反应工程和分子热力学计划的部分共同资助支持，其主要目标是开发空间组织的氧化还原反应网络，这些网络可以通过电信号控制来管理运输、指示反应活性和分离产品。总体目标是通过开发控制反应物分子和粒子到反应位置的传递以及控制零维和一维电化学纳米结构中的反应性来实现的。该团队还将这些纳米结构结合在一起，开发出对级联反应的完全三维控制，以产生矢量控制的反应网络(VCRN)。第一个目标是开发高精度的纳米结构，通过使用基于金属绝缘体的多层堆叠纳米孔和分级组织的组件同时控制传输和反应来支持VCRN。第二个目标是探索如何利用电化学势来控制与其中一个电极结合的酶的活性。利用辣根过氧化物酶(HRP)作为氧化还原酶的模型酶，在电化学零模波导的超高灵敏度环境中，通过荧光氧化还原反应将非荧光反应物转化为荧光产物，从而跟踪电极结合酶的本征反应活性。这些能力正在使用一系列严格的单酶动力学实验进行组合和测试，在这些实验中，HRP在可用位置之间移动，并在与电化学电位控制信号耦合时测试内在反应活性。这项工作的最终目标是利用对单一反应事件的控制来创建VCRN的制备规模能力。为了测试这一能力，两种酶的电化学调节的反应系统正在以空间协调的方式与单个反应相耦合，并用于将反应产物输送到下游收集点。这个项目的影响超出了化学分析的主要学科，特别是在级联反应的一般领域-化学合成中使用的强大结构，例如，用于酶生物燃料电池，以捕获燃料来源的全部电化学还原能力。该奖项反映了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。

Reactions are the central events of chemistry and controlling their behavior and the locations where they occur is at the heart of chemical measurements and making new chemicals. Ideally, scientists want to design reactions so they occur rapidly, make efficient use of all the chemical participants, employ inexpensive chemicals and environmentally friendly conditions, and produce easily-isolated chemical products. In nature, such as in biological cells, these stringent objectives are achieved by spatially-organized reaction networks. Dr. Paul Bohn's research team at the University of Notre Dame mimics nature by designing and developing networks of reactions whose behavior is controlled by electrical stimulus and whose location is defined by the size of the reaction vessel. In their work with electron-transfer reactions, they carefully build specially-designed structures from nanometer-sized materials, whose nature and placement leads to particular, well-defined, and highly efficient reactions occurring in specific locations. Furthermore, electrical control of the location-specific reactions and movement of nearby liquid allows for shuttling of chemical products from one reaction site to another one downstream, where they are used as the chemical starting materials for another defined reaction process. All the reactions are sped up using enzymes, nature's chemical reaction catalysts. The Bohn team is developing an understanding of how electrical voltages can be applied to control the activity of catalysts. The research efforts are integrated with new education and training programs that cut across disciplinary lines within the University of Notre Dame and combine talents from multiple universities. In the process, these activities address specific NSF goals including development of a diverse, globally competitive science-technology-engineering-mathematics workforce; increased partnerships between academia and industry; and improved economic competitiveness.The principal goal of this project supported by the Chemical Measurement and Imaging Program and partial co-funding from the Molecular Separations, Electrochemical Systems, and Process Systems, Reaction Engineering and Molecular Thermodynamics Programs at NSF is to develop networks of spatially-organized redox reactions which can be controlled by electrical signals to manage transport, dictate reactivity, and isolate products. The overall goal is addressed by developing control over delivery of reactant molecules and particles to a reactive site as well as control over reactivity, within zero- and one-dimensional electrochemical nanostructures. The team also combines these nanostructures to develop full three-dimensional control over cascade reactions to produce vectorially-controlled reaction networks (VCRNs). The first objective is the development of high-precision nanoscale architectures to support VCRNs by simultaneous control over transport and reactivity using both metal-insulator multilayer stack-based nanopores and hierarchically-organized assemblies. The second objective explores ways in which electrochemical potential can be used to control activity of enzymes bound to one of the electrodes. Using horseradish peroxidase, HRP, as a model oxidoreductase enzyme, the intrinsic reactivity of the electrode-bound enzyme is followed using a fluorogenic redox reaction that converts a non-fluorescent reactant into fluorescent product within the ultrahigh sensitivity environment of an electrochemical zero-mode waveguide. These capabilities are being combined and tested using a set of stringent single enzyme kinetics experiments, in which the HRP is moved among the available locations and tested for intrinsic reactivity when coupled to an electrochemical potential control signal. The ultimate goal of this work is to leverage control of single reaction events to create a preparative scale capability for VCRNs. To test this capability, two-enzyme electrochemically-modulated reaction systems are being coupled to individual reactions in a spatially coordinated manner and used to deliver the reaction products to a downstream collection point. This project has impact outside the principal discipline of chemical analysis, especially in the general area of cascade reactions - powerful constructs in chemical synthesis that are used, for example, in enzymatic biofuel cells to capture the full electrochemical reducing power of fuel sources.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.