A Nanomembrane-Based Nucleic Acid Sensing Platform

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1065652ChangIntellectual Merit: Portable and multi-target DNA/RNA diagnostics requires a rapid, field-usable, simple to operate, regenerable and economical biosensor system. The proposed new platform is based upon the integration of several newly discovered electrokinetic phenomena in nanoporous membranes that promise to extend traditional label-free electrochemical and capacitance/conductance biosensors to the requisite robustness, sensitivity (pM detection limit of about one million molecules), selectivity (SNP discrimination with only one mismatch at a ~30-base docking sequence for a kb-long DNA/RNA) and assay speed (5 minutes) for on-field nucleic acid detection. These new detection features are results of nonlinear/selective ionic conductance, dynamically controlled ion depletion/selectivity, concentration polarization, molecular dielectrophoresis, on-chip pH control, electrohydrodynamics, surface charge inversion by nucleic acid hybridization all new electrokinetic and electr static phenomena of nanoporous membranes that are only recently understood or discovered with the latest nanofabrication and imaging capabilities. The proposed work will optimize and integrate these new physical phenomena into an automated membrane sensing platform for hand-held DNA/RNA devices suitable for field applications by scientifically scrutinizing the detailed non-equilibrium electrokinetic phenomena and by exploiting the latest nano/microfabrication technologies.Broader Impacts: The proposed work will provide PhD and post-doc students with an unusually rich educational experience. It involves fundamental scientific studies of new electrokinetic and membrane physics/chemistry, the latest micro/nano-fabrication technologies, contagious disease health science,molecular genetics and genomics, ecology and miniature instrumentation design to develop prototypes that can have a significant impact on biological research and, more commercially, the biotechnology industry sector. The PI has significant track records of placing group members in tenure-track faculty positions (11 in the last 5 years) at major research universities, including 3 NSF Career Awardees, 3 women and 1 African American. Educational opportunities also extend to undergraduates and local high school students/teachers through an active summer outreach program in the PI's laboratory. Almost all of the undergraduate researchers from the PI's lab go on to top PhD programs. Significant opportunities exist for international collaborations due to the PI's strong ties to institutions in Taiwan, Korea, Europe, and China through his capacity as the founding and chief editor of Biomicrofluidics, an American Institute of Physics journal with high impact factor.Scientific and Technological Impact: A viable portable (handheld) and label-free DNA/RNA detection platform for viral assays, bacteria detection etc. will spur a major technological advance in the biosensor industry, as it will fundamentally transform pathogen detection methodology for medical, environmental, agricultural and biodefense applications by eliminating the time-consuming PCR or reverse transcription PCR step and the costly/bulky/personnel-intensive optical detectors of fluorescent sensing platforms. Robust and portable RNA detection technologies have yet to appear because of several outstanding technological challenges---slow assay time (longer than RNA degradation time), sensitivity to sample debris and chemical content, and expensive/bulky detection instrumentation. The proposed project investigates, with complementary fundamental and fabrication efforts, several new nanoporous membrane phenomena that promise to alleviate these obstacles and integrates them onto a multiplex chip platform that may lead to a new molecular sensing product. The project can hence impact both nano science and nano biotechnology.