February 14, 2014 |
3:00 am to 4:30 pm
ERB Room 228 | Seminar Flyer
Dr. Xiao Ma
Dept. of Mechanical Engineering, Iowa State University; Department of Cell Biology at University of Texas Southwestern Medical Center at Dallas.
Smart surface or biotic‐abiotic interface design has attracted considerable attentions and interests, due to the feasibility to modulate the physical and chemical properties of a nano‐ or micro‐ scale surface via certain external stimuli, and thus has tremendous application potentials in medical and nano device design and fabrication. One of the most critical challenges on such design is the efficient control of the external stimuli for successful modulation upon the performance of the surface/interface. Electrostatic actuation based modulation on binding and force interaction between coagulation enzyme thrombin and DNA aptamer has been implemented and verified to satisfy the demands. Photolithography and soft lithography were utilized to construct the nanostructure of the thrombin‐aptamer binding pair, and atomic force microscopy (AFM) surface topographic scan with height measurement was conducted to validate the binding state of the complex. Our results showed that the binding complex could be successfully dissociated under positive electrical potentials, while the structure was maintained under zero or moderate negative electrical potential. On the other hand, AFM based dynamic force spectroscopy (DFS) was applied to investigate the force interaction between thrombin and aptamer under electrical field conditions. Our results exhibited that under positive electrical potential, the force interaction was substantially attenuated compared to those under zero and negative electrical potential, which provided a solid validation for the first experiment. Rigorous statistical analysis were carried on to reveal the rupture force distribution, elementary binding force scale, and loading rate effect, and important kinetic coefficients were estimated from fitting the experimental results to a single energy barrier model. Our research not only proves the availability of electrical mechanism on actuation and modulation of biomolecular interface, but also deepens the understanding upon the physical mechanism behind the complex binding behavior.
Xiao Ma earned his Ph.D degree in Department of MechanicalEngineering from Iowa State University in 2013. His research interestsmainly focused on experimental and computational macro/nano mechanics,biomechanics, nanofabrication, and surface characterization. He receivedboth research and teaching excellence awards from Iowa State University duringthe ngraduate studies. He is currently a post?doctorial research fellow inDepartment of Cell Biology at University of Texas Southwestern MedicalCenter at Dallas, and his research focuses on computational biology, cellmigration and mechanotransduction.