Micromagnetic-DEP tweezers for Studying Fibronectin Fragment Mechanics

Lizhi Cao

Abstract: A variety of tools are available for studies of single molecule biophysics, these include: atomic force microscopy (AFM), optical and magnetic tweezers, biomembrane force probe (BFP), among other techniques. However, few techniques exist for parallel high throughput analysis, and to our knowledge none have been coupled to microfluidic systems for coupled biochemical assays. We have developed a microfabricated system using opposing magnetic and dielectrophoresis (DEP) forces to study the conformational changes and unfolding behavior of magnetic bead-coupled engineered fibronectin protein fragments. Specifically, our system may allow for the study of forced unfolding of fibronectin type III repeats on a massively parallel scale, and offers the potential for integration with biochemical assays to assess the functional consequences of forced unfolding. More broadly, the micromagnetic-DEP system developed here can be extended to study antibody-antigen interactions, as well as other protein-protein interactions.

Lizhi Cao is a 5th year Ph.D. student in the School of Biomedical Engineering (Research Advisor: Tom Barker).  He obtained his undergraduate degree in bioengineering from UC Berkeley in 2008.

Control of Si Nanowire Structure via Surface Chemistry

Naechul Shin

Abstract: An ability to engineer the structure of semiconductor nanowires is essential for tuning their optical, electrical, and thermal transport properties. While manipulation of growth conditions offers an empirical route to control both the orientation of nanowire growth and the stacking of individual atomic layers, a fundamental understanding of chemical bonding that underlies these changes remains unclear and limits rational control of the process. In this talk, we will discuss our recent real-time in-situ spectroscopic studies of Si nanowires synthesized via the vapor-liquid-solid (VLS) mechanism and highlight the importance of adsorbed hydrogen atoms in controlling nanowire structure. The use of this knowledge to fabricate user-programmable nanowire superstructure will also be presented.

Naechul Shin is a 5th year graduate student in the School of Chemical and Biomolecular Engineering (Research Advisor: Michael Filler). He received a B.S. in 2006 and a M.S. degree in 2008, both in chemical engineering, from Seoul National University.