Enhanced capillary electrophoretic and hydrodynamic chromatographic separations on microchip devices using a combination of electrokinetic and hydrodynamic flows

0854179dutta这项由化学和生物分离项目颁发的NSF奖支持怀俄明大学的Debashis Dutta教授开发的微/纳米流体设备，该设备可以使用电动和压力驱动流的组合来提高毛细管电泳（CE）和流体动力色谱（HDC）分离的分辨率。此外，本文还将基于DNA分子在压力驱动流场中的剪切迁移，设计一种新的HDC分离方法。该方法的发展将消除使用具有与溶质直径相当的横向尺寸的分析柱的必要性，以实现高效的HDC分离。上述具体目标将通过PI实验室开发的微流体和纳米流体装置来实现，这些装置可以利用电力在芯片上产生压力驱动的流动。在所提出的装置中，基于硅酸盐的溶胶-凝胶膜被用来阻断沿着系统中产生压力梯度的通道产生的电渗透流。由此产生的压力驱动流随后被引导到分析柱，以驱动或加强分离过程。值得注意的是，这些设备能够在芯片上产生压力梯度，通过最小化死体积，可以精确和动态地控制分析柱中的流体动力流速。此外，由于这种能力是利用电动力实现的，因此它允许在微流体和纳米流体网络中同样容易地产生压力梯度。预计拟议的工作也可能对CE和HDC技术以外的分离研究产生广泛影响。这是因为与文献中描述的其他设计相比，这里提出的微泵易于制造并且易于集成到微/纳米流体分离系统中。这种微型泵的这一方面可能会吸引其他实验室采用它进行自己的研究。此外，所提出的装置在微/纳米流体管道中同样容易地产生流体动力流动的能力使其成为一种有价值的研究工具，不仅可以小型化现有的压力驱动分离方法，还可以研究依赖于微/纳米通道中压力驱动流场的新分离方案。最后，本文提出的工作将建立一种廉价和简单的方法，用于在微/纳米通道中制造低电阻和耐用的硅酸盐基溶胶-凝胶膜，与目前常用的聚合物基膜相比，可以在更广泛的分析条件下使用。虽然微/纳米科学的进步正在彻底改变我们理解当今世界的方式，但将这些知识整合到本科和研究生教育中却进展缓慢。这个问题在怀俄明州这样的州尤为突出，那里的高科技产业发展远远低于全国平均水平。然而，随着纳米科学和纳米技术在怀俄明州经济各个部门的应用的增加，对这些科学领域培训未来劳动力的需求也在不断增长。作为怀俄明州唯一的四年制大学，怀俄明大学（UW）承担着提供必要的基础设施以满足这些需求的主要责任。本提案中描述的工作将有助于解决这一问题，为本科生和研究生提供将纳米科学和纳米技术应用于基础和应用研究的重要领域的教育和研究经验，例如这里描述的提高CE和HDC方法分辨率的具体项目。除了培训研究生和本科生外，该计划还提出了三项额外的教育活动，旨在将研究成果传播给广泛的受众，并直接让高中生参与研究活动。这将包括将提议的CE和HDC分离方法纳入华盛顿大学研究生水平的化学课程，并为高中生启动暑期研究学徒计划。与此同时，PI还将与中央怀俄明学院（CWC）制定一项外展计划，以扩大少数民族和贫困社区的参与，该学院约有20%的土著美国人和80%的第一代大学生。

0854179DuttaThis NSF award by the Chemical and Biological Separations program supports work by Professor Debashis Dutta at the University of Wyoming to develop micro-/nanofluidic devices that can enhance the resolving power of Capillary Electrophoretic (CE) and Hydrodynamic Chromatographic (HDC) separations using a combination of electrokinetic and pressure-driven flows. In addition, the proposed work will also design a novel HDC separation method for DNA molecules based on their shear-induced migration in a pressure-driven flow field. The development of this method will eliminate the necessity to use analysis columns that have lateral dimensions comparable to the solute diameter in order to realize high-efficiency HDC separations. The Specific Aims described above will be accomplished using micro- and nanofluidic devices developed in the PI's laboratory that can generate a pressure-driven flow on-chip using electrical forces. In the proposed devices, a silicate based sol-gel membrane is used to block electroosmotic flow generated along a channel yielding a pressure-gradient in the system. The resulting pressure-driven flow is then guided to an analysis column to drive or enhance a separation process. It is worth noting that the ability to generate pressure-gradients on-chip in these devices provides a precise and dynamic control over the hydrodynamic flow velocity in the analysis column through minimization of dead volumes. Moreover, because this capability is realized using electrokinetic forces, it allows the generation of pressure-gradients within micro- and nanofluidic networks with equal ease. It is anticipated that the proposed work could also have a broad impact on separations research outside of the CE and the HDC techniques. This is because the micro-pump presented here is easy to fabricate and simple to integrate to micro-/nanofluidic separation systems compared to other designs described in the literature. This aspect of the proposed micro-pump could make it attractive for other laboratories to adopt it for their own research. Further, the ability of the proposed devices to generate hydrodynamic flows in micro- and nanofluidic ducts with equal ease makes it a valuable research tool for not only miniaturizing existing pressure-driven separation methods but also studying new separation schemes that rely on a pressure-driven flow field in micro-/nanochannels. Finally, the proposed work will establish an inexpensive and simple procedure for fabricating low resistance and durable silicate based sol-gel membranes in micro-/nanochannels that can be employed under a wider range of assay conditions compared to polymer based membranes commonly used today.While advances in micro-/nanoscale science are revolutionizing the way we understand our world today, the integration of this knowledge into undergraduate and graduate education has been slow. The problem is particularly prominent in states like Wyoming where the development of high tech industries has been well below the national average. However, with increases in the application of nanoscience and nanotechnology to various sectors of the Wyoming economy there is a growing demand on training future workforce in these scientific areas. As the only four-year college in the State of Wyoming, the University of Wyoming (UW) carries the primary responsibility for providing the required infrastructure to meet these demands. The work described in this proposal will help to address this problem by providing educational and research experience to undergraduate and graduate students in applying nanoscience and nanotechnology to important areas of basic and applied research, such as the specific projects described here for improving the resolving power of CE and HDC methods. Besides training graduate and undergraduate students, the PI proposes three additional educational activities aimed at disseminating the results of the research to a broad range of audiences, as well as directly involving high school students in research activities. This will include incorporating proposed CE and HDC separations methods into a graduate level chemistry course at UW, and initiating a summer research apprentice program for high school students. At the same time, the PI will also develop an outreach program with the Central Wyoming College (CWC) that has about 20% Native American and 80% first-generation college student population to broaden the participation of minorities and underprivileged communities.