Thomas Beebe, Professor
University of Delaware
006 Lammot duPont Lab
Newark, DE 19716
(b. 1960) B.A. 1982, Franklin & Marshall College; Ph.D., 1987, ersity of Pittsburgh; Postdoctoral, 1987 – 1989, Lawrence Berkeley and Lawrence Livermore Labs
My research group focuses on the surface chemistry, surface biology, and surface physics of systems ranging from living neurons, to monolayers on graphite, to air pollution particulates, to fuel cell membranes and their catalyst layers. Space only permits two projects to be summarized below.
We engage in multi-disciplinary projects that employ state-of-the-art surface analytical tools including scanning tunneling microscopy (STM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and Auger electron spectroscopy (AES).
Molecule corrals are nanometer-sized pits that can be formed with a high degree of control on the basal plane of highly oriented pyrolytic graphite (HOPG). They have a number of unique features that make them useful for several purposes: (1) They can be produced by a simple benchtop oxidative process in an oven operating in the ambient air, producing CO2 (g); (2) They can be produced with a diameter from one nanometer to several microns by varying the total reaction time used to produce them, and they can be produced in both monolayer-deep and multilayer-deep versions, with depth control; (3) They are produced in an inherently parallel process, covering the entire surface; (4) They can be produced with a density that ranges from less than 1 per µm2 to more than 100 per µm2; (5) Once formed, they can be used in a range of diverse applications and fundamental studies. Using patterned arrays of molecule corrals, we are currently working on templated nanostructures and controlled polymerization of corral-bound molecular arrays, producing novel nanostructures with conductivity along molecular chains.
This project is aimed at developing biomaterial bridges that can stimulate and control nerve regrowth in patients suffering from central nervous system damage and disease. Highly specific interactions between biomolecules, interactions such as cell-surface ligand-receptor recognition, antibody-antigen binding, and complementary double-stranded DNA hybridization, play a primary role in governing the exquisite molecular recognition process in numerous biological functions. The direct measurement of the forces involved in these biological events can now be studied by AFM. Atomic force microscopy, with its high force sensitivity and capability of operation under physiological liquid environments, is well suited for studies of such biological interactions. A unique force analysis method based on Poisson statistics has been developed and exploited in our group. This method allows one to determine the magnitude of individual bond-rupture forces as well as nonspecific interactions using the AFM. Using our surface chemistry expertise, we place chemical and biological groups on the AFM tips and surfaces, and all modified surfaces are characterized by various surface-sensitive techniques, including XPS, TOF-SIMS, and contact-angle measurement. These studies are helping us to understand the ligand-receptor interactions at protein interfaces.
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