Associate Professor (Physics and Astronomy)

Office: Clippinger 357A
Phone: (740) 593-1694
Fax: (740) 593-0433
Email: tees@ohio.edu

There are two ongoing research areas in my lab. Both involve bioadhesion and both involve observing cell-cell interactions one cell (or particle) at a time.

The first area is on the single cell-scale, but uses adhesion molecules as a link to the molecular scale. Capillaries (the smallest blood vessels in the body) are significantly smaller than most of the blood cells that have to flow through them.  During inflammation and bacterial infection, white blood cells can get trapped in capillaries, especially in the lung.  The biophysics of the process is still poorly understood.  Based on the physics of the capillary environment, it is hypothesized that cell arrest in capillaries can involve both mechanical and biochemical adhesive forces.  To test this hypothesis, an adhesion assay has been developed in which cells are sucked into small, capillary-sized glass tubes (called micropipettes) that we coat with adhesion molecules.  This "flow chamber for the capillary microcirculation" will help to resolve basic questions on the mechanisms of cell trapping in capillaries under many different physiological conditions.  Chemical and Biomolecular Engineering Ph.D. student Prithu Sundd works on this project.  This work is done in collaboration with Douglas J. Goetz in Chemical and Biomolecular Engineering.  The work has been supported by an award from the American Heart Assocation and is now supported by a NSF CAREER grant to the PI.

The second involves single molecule forced unbinding of receptor-ligand bonds.  Another major thrust of my lab is studies of the single molecule biophysics using forced unbinding with a microcantilever biosensor.  Since the function of adhesion molecules is to hold cells together, the biophysics of adhesion can be studied by pulling interacting molecules apart.  The fiber biosensor is a long (mm), thin (µm) piece of optical fiber that acts as a highly sensitive spring to apply small, biologically relevant forces to the bonds. The fiber is coated with adhesion molecules and so are latex spheres. Beads are moved into contact with the fiber using a micropipette. This allows the formation of a small numbers of bonds. When the bead is pulled away, the fiber deflects from its original position if a bond is present. The amount of deflection (which is seen under the microscope) is a measure of the force on the bonds. Physics and Astronomy graduate student Sulaiman Kareem works on this project and work on forced unbinding of Hydroxyproline-Rich Glycoproteins in collaboration with Marcia Kieliszewski is funded by a grant from BNNT.

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