ABSTRACT

Abstract
CTS-0404124
S. Han, University of New Mexico

Intellectual Merit: This research team will investigate the transport of complex fluids in channels of nanoscale dimensions. Our scientific goal is to render an accurate description of biomolecular structural changes, reaction, and transport in nanochannels as a function of built-in as well as externally applied potentials. The understanding of such fluid and molecular transport, which cannot be accurately modeled by continuum mechanics, is imperative for the development of a new generation of devices to address the urgent need for efficient separation of proteins in the context of their application to proteomics, environmental science, and advanced diagnostics. The technological and scientific outcome from this research will enable high throughput separation, purification, identification, and determination of structure-function relationships of biomolecular species and biomolecular complexes. The proposed activities consist of two main categories.

Nanofluidics of Complex Aqueous Solutions. The team will investigate the following physical processes to fundamentally understand the behavior of aqueous solutions containing dissolved proteins passing through nanochannels: electro-osmosis in nanochannels with overlapping (or nearly overlapping) double layers; impact of a field-effect-transistor-like gate electric field on solution pH during electrophoresis; and effect of fluid inhomogeneity on electrokinetic phenomena. The team will employ both theoretical (quasi-continuum model, molecular dynamics simulations, and Boltzmann kinetic model) and experimental (fluorescence spectroscopy; electrochemical impedance spectroscopy; substrate-potential-modulated, time-resolved Fourier transform infrared spectroscopy; and nanomachined-waveguide-assisted Fourier transform infrared spectroscopy) techniques to predictably describe and probe the transport of protein molecules in electrolyte buffer solutions.

Applied Bioseparation and Analysis. The team will exploit this fundamental understanding of nanofluidics to develop advanced bioseparation schemes based largely on nanoelectrophoresis. Nanofluidic Switching relies on modulation of the zeta-potential in the nanochannels driven by a gate potential applied to the semiconductor substrate surrounding the nanochannels, but separated from the fluid by a thin oxide. The field effect transistor (FET) analogue based on this nanofluidic switching concept may potentially lead to integrated nanofluidic circuits consisting of all solid-state electrokinetic pumps, valves, and filters. It will also allow nanochannel pH modulation, which can then be applied in Nanoelectrochromatography, allowing target proteins to be bound and released by changing the voltage on the semiconductor substrate.

Broader Impact: In addition to Sandia National Laboratories and Computational Fluid Dynamics Research Corporation, the team has an on-going collaboration with Intel Corporation in the area of microfluidic protein separations, which will synergistically enhance the scientific and technical impact of proposed research. The University of New Mexico (UNM) will benefit from the established systems biology program at Washington State University (WSU), while WSU will benefit from UNM's nanofabrication capability. The proposed research program offers an interdisciplinary educational environment to mentor 1 postdoctoral researcher, 5 graduate students, and 3 summer undergraduate students. The information gathered from research also provides a knowledge base for course development. The team will develop a course in Non-Continuum Fluid Mechanics at UNM during the 2nd year of this research. The principal investigator (PI) and co-PIs will also actively participate in the development of courses in nanofabrication, bioseparation, spectroscopic imaging, and optics. The course content will substantially draw from the proposed research and reflect its latest advances. The new elective courses will broadly impact the students from various disciplines that range from chemical engineering, to biology, to mathematics. Such course development serves the goal of the School of Engineering at UNM to launch a degree program in Nano/Micro Materials, Devices, and Systems (NMMDS). Educational research in this scientifically fertile area will serve the students who desire to pursue a career that promises rapid growth and potentially significant societal impact. In addition to graduate students, the PIs will continue to actively involve underrepresented undergraduate students with research. The outreach program will be coordinated with Diversity Programs and Engineering Student Programs at UNM to actively educate prospective high school students of the research-oriented educational opportunities. At WSU, the College of Engineering and Architecture organizes three 6-day summer youth camps, called Native Youth Exploring Engineering (NY.EE) and a new HY.EE equivalent for Hispanic high school students. NY'EE attracts about eighty 9th-11th-grade students from WA, ID, MT and OR Indian reservations. All these outreach programs have significant potential to improve the percentage of high school students pursuing post-secondary education and increasing the enrollment of minority students (especially Hispanics and Native Americans) and women. The educational plan directly addresses the expressed needs of both students and faculty at UNM and WSU. This project will also enhance the NSF"s EPSCoR initiative in nanomaterials in
New Mexico.

Research and Education Themes: Nanoscale Structures, Novel Phenomena, and Quantum Control; Biosystems at the Nanoscale; and Multi-scale, Multi-phenomena Theory, Modeling and Simulation at the Nanoscale.

This award is funded by the Division of Chemical & Transport Systems and Design, Manufacture & Industrial Innovation.

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