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Special MNT Seminar - Wednesday, March 19, 2014, 3:00-4:00, 271 Batcheller Technology Center

Revealing Protein Dynamics by Integrating Molecular Dynamics Simulations with Neutron Scattering Experiments, Dr. Liang Hong, Center for Molecular Biophysics, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, Web: http://cmb.ornl.gov/people/liang

Protein, the engine of life, carries out most functions in living things on the earth through characteristic modulation of its three-dimensional structure over time. Understanding the microscopic nature of the protein internal motion and its connection to the function and structure of the biomolecule is a central topic in biophysics, and of great practical importance for drug design, study of diseases, and the development of renewable energy, etc. Under physiological conditions, protein exhibits a complex dynamics landscape, i.e., a variety of diffusive and conformational motions occur on similar time and length scales. This variety renders difficult the derivation of a simplified description of protein internal motions in terms of a small number of distinct, additive components. This difficulty is overcome by our work using a combined approach of Molecular Dynamics (MD) simulations and the state-of-the-art Neutron Scattering experiments. Our approach enables quantitative characterization of distinct protein motions, furnishing an in-depth understanding of the connection between protein structure, dynamics, energy landscape and function.

For more information, contact Erik K. Hobbie, 701-231-6103, erik.hobbie [at] ndsu [dot] edu

Special MNT Seminar - Thursday, March 27, 2014, 3:30-4:30, 271 Batcheller Technology Center

Single Molecule Bioelectronics, Dr. Yongki Choi, Department of Physics and Astronomy, University of California Irvine

Nanoscale electronic devices like field-effect transistors have long promised to provide sensitive, label-free detection of biomolecules.  In particular, single-walled carbon nanotubes have the requisite sensitivity to detect single molecule events, and have sufficient bandwidth to directly monitor single molecule dynamics in real time.  Our recent work has demonstrated this premise by monitoring the dynamic, single-molecule processivity of three different enzymes: lysozyme, protein Kinase A, and DNA polymerase I.  With all three enzymes, single molecules were electronically monitored for 10 or more minutes, allowing us to directly observe rare transitions to chemically inactive and hyperactive protein conformations.  The high bandwidth of the nanotube transistors further allow every individual chemical event to be clearly resolved, providing excellent statistics from tens of thousands of turnovers by a single enzyme. Besides establishing values for processivity and turnover rates, the measurements reveal variability, dynamic disorder, and the existence of intermediate states.  Initial success with the three enzymes indicates the generality and attractiveness of the nanotube devices as a new tool to complement existing single molecule techniques.  Furthermore, our focused research on transduction mechanisms provides the design rules necessary to further generalize this architecture.

For more information, contact Erik K. Hobbie, 701-231-6103, erik.hobbie [at] ndsu [dot] edu

Special MNT Seminar - Monday, March 31, 2014, 3:00-4:00, 271 Batcheller Technology Center

Directed Assembly of Colloidal Particles at Liquid Crystal Interfaces, Dr. Mohamed Amine Gharbi, University of Pennsylvania

Colloidal particles organize spontaneously at fluid interfaces owing to a variety of interactions to form well-organized structures that can be exploited to synthesize advanced materials. While the physics of colloidal assembly at isotropic interfaces is well understood, the mechanisms that govern interactions between particles at complex fluid interfaces are not yet clearly established. In particular, nematic and smectic liquid crystal materials offer important degrees of freedom that can be used to direct particles into new structures. In this work, I report the behavior of solid micrometric beads with homeotropic anchoring confined at interfaces of liquid crystal films. First, I will detail the behavior of spherical solid particles at planar nematic liquid crystal (NLC) interfaces. Subsequently, I will report the behavior of particles at more complex NLC interfaces. I will review how the competition between anchoring conditions, liquid crystal elasticity, and topology of curved surfaces is responsible for the formation of new ordered structures in a self-assembly process. Second, I will report the behavior of silica beads confined at interfaces of thin smectic films. I study the interactions and self-assembly of these particles in both supported and free standing films. When particles are captured in thin membranes, they induce distortions of the smectic interface to satisfy wetting properties at particle boundaries, leading to capillary interactions. These forces compete with elastic ones induced by the distortion of the smectic layers. The resulting potential drives assembly of the spheres into new different structures. Recent progress in understanding the mechanism of particle self-organization is presented.

For more information, contact Erik K. Hobbie, 701-231-6103, erik.hobbie [at] ndsu [dot] edu

Special MNT Seminar - Thursday, April 3, 2014, 3:30-4:30, 271 Batcheller Technology Center

Imaging of Complex Biological Systems at the Sub-Cellular, Cellular and Multicellular Levels, Dr. Alexander Khmaladze, University of Michigan

Non-invasive nature of optical microscopy enables researchers to study a great variety of materials under conditions approaching or similar to their "natural" environment. This is especially relevant to live biological specimens, which can be studied both in-vitro and in-vivo, providing a unique insight into the dynamic processes occurring in the live organisms. In recent years, the emphasis has been shifting towards the technologies that combine several different imaging techniques to study a particular system. Each technique then allows measuring a partially overlapping set of parameters, leading to deeper understanding of the processes occurring within that system. This talk presents several imaging and spectroscopic techniques, namely dual-wavelength digital holographic microscopy, hyperspectral coherent anti-Stokes Raman imaging and spontaneous Raman spectroscopy. I will show how these techniques proved to be useful to answer specific questions, and also how they can be applied to solve a wide range of problems in physics, chemistry, biology and medicine. Moreover, by combining them, a single objective, such as a comprehensive study nanoparticles entry into cells and tissues, can be achieved. Due to interdisciplinary nature of these research topics, they are particularly well suited for involving researchers with various scientific backgrounds and interests. This research also provides rich opportunities for students to explore and gain knowledge in optical design, software programming, mathematics and nano-biology.

For more information, contact Erik K. Hobbie, 701-231-6103, erik.hobbie [at] ndsu [dot] edu

Special MNT Seminar - Tuesday, April 8, 2014, 3:30-4:30, 271 Batcheller Technology Center

Macromolecules on Lipid Membranes: Brownian Motion, Conformational Dynamics, and Local Perturbations, Dr. Eugene Petrov, Max Planck Institute of Biochemistry, Department of Cellular and Molecular Biophysics, Martinsried, Germany

Interaction of polymer molecules and colloidal particles with lipid membranes is one of the important problems of the modern bio-inspired soft matter physics. Its understanding provides an insight into mechanisms of interaction of biological macromolecules with cell membranes. What is the effect of the lipid membrane on the conformational dynamics and Brownian motion of membrane-bound polymer molecules? How lipid diffusion and phase separation in the membrane are affected by local perturbations induced by macromolecules? In my talk I will address these and other related questions using my recent results for model membrane systems and macromolecular structures including DNA, DNA origami, fd-virus, and artificial FtsZ-based membrane cortex. Experimental results obtained using fluorescence video-microscopy, fluorescence correlation spectroscopy, and single-particle tracking will be compared with Monte Carlo simulations and theoretical models. I will discuss implications for understanding important biological issues such as anomalous diffusion in cell membranes, effect of the membrane cytoskeleton on cold-shock resistance of organisms, and spontaneous DNA uptake by living cells

For more information, contact Erik K. Hobbie, 701-231-6103, erik.hobbie [at] ndsu [dot] edu


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Materials and Nanotechnology program
Phone: (701) 231-6456
Fax: (701) 231-6524

Last Updated: Monday, March 17, 2014 8:52:11 AM