叶涛教授
School of Natural Sciences, 5200 North Lake Road, University of California, Merced, California 95343
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时间：4月3日（星期四）上午10:00 AM
地点：唐仲英楼A313
The recognition of target molecules by DNA probe molecules tethered to surfaces is at the heart of a wide range of sensors and microarrays. Yet, although established models can predict the thermodynamics and kinetics of DNA hybridization in the solution phase, our understanding of the biophysics of DNA probes on surfaces remains in its infancy. A major challenge is that little is known about the spatial arrangement and conformations of these probe molecules, which may have a profound impact on molecular recognition on surfaces. Among the current techniques, atomic force microscopy (AFM) is the only one that is potentially capable of visualizing the individual DNA molecules on biosensor surfaces in situ and with nanometer resolution. Yet, existing AFM studies on DNA probes have only achieved poor spatial resolution, which severely hampers the utility of AFM.
We recognize that a major barrier to high-resolution imaging is the fluctuation of DNA molecules on surfaces. By exploiting the transient electrostatic pinning enabled by an applied electrochemical potential, we have enabled AFM to visualize the conformational changes of single DNA molecules tethered to gold. Our study has revealed an extreme sensitivity to the nanoscale environment: the electrostatic interaction of the DNA with the surface is dominated by defects in the passivating self-assembled monolayer (SAM) and that the SAM, often regarded as a static structure, is not only high mobile but is actively remodeled by the DNA at different applied potentials. Moreover, by directly visualizing single hybridization events, we have provided nanoscale and single molecule level evidence that the hybridization efficiency is impacted by the presence of neighboring probe molecules. Such molecular level insights into hybridization on surfaces may inform new strategies to engineer more robust and reliable DNA sensors.
Bio-sketch:
Dr. Tao Ye received his B.S. degree in Chemistry from Peking University, and Ph.D. (Chemistry) from University of Pittsburgh. He received postdoctoral training from the group of Paul Weiss in the Pennsylvania State University. In 2007, he began his independent career at UC Merced, the tenth and the newest campus of the University of California system. His research group is developing sophisticated nanoscience tools, especially scanning probe microscopy to position and measure single molecules with nanometer resolution, dynamically activate the functions of individual biomolecules on surfaces, and develop artificial analogs of biological motors.