Ph.D., Macromolecular Science and Engineering, Case Western Reserve University, 2000
M.S., Engineering Science, New Jersey Institute of Technology, 1997
B.S., Materials Science and Engineering, Lehigh University, 1994
Jan 2007 - Present - Associate Professor, Biological Systems Engineering Department, Virginia Polytechnic Institute and State University, Blacksburg, Va.
Sept. 2002 - Dec. 2006, Research Chemist, USDA/ARS, Beltsville, Md.
Apr. 2000 - Sept. 2002 - Advanced R&D Engineer, Polymer Diagnostics, Inc. (a division of the PolyOne Corp.), Avon Lake, Ohio
Jan. 1995 - Feb. 1996 - Project Engineer, Utility Development Corporation, Livingston, N.J.
I have mentored 23 undergraduate students in my research laboratory in the past 5 years. Currently, I am the director of the NSF-REU Site: Bioprocess Engineering for Sustainability at Virginia Tech.
The Renewable Materials Research Group is interested in how polymer molecules change shape and how that can be used advantageously to process polymers in new ways. We want to design scalable, low energy processes for renewable materials. We are pursuing innovative materials and interesting processing:
Self-assembly. “Template” proteins are short, hydrophobic proteins that form β-sheets to minimize free energy. “Adder” proteins are hydrophilic, α-helical proteins that are stable by themselves. However, when mixed with a template protein, adder proteins will undergo α-helix to β-sheet conformation change. The two proteins cooperatively self-assemble from the nm to the μm scale into large amyloid fibers 10-20 μm across. It is possible to control the shape and properties of the fiber through protein choice (Scheme 1).
Since proteins can be genetically encoded, we are engineering cells to express “template” and “adder” proteins that self-assemble into fibers. In nature, protein fibers form the basis for many structural components like muscles, ligaments, feathers, and spider webs. Large amyloid fibers do not require melt- or electro-spinning to process. Self-assembly can be viewed as nature’s “additive manufacturing” (AM) process, just like 3D printing. As such, it may be possible to genetically encode large-scale components if the large amyloid fibers could be coaxed to continue to self-assemble (like the tube at the end of Scheme 1). This requires larger or “mesoscale” self-assembly (MESA). MESA is more difficult than molecular level assembly because you need a large scale, directed force to motivate the objects to self-assemble in an organized fashion. The Renewable Materials Research Group has ongoing projects in protein engineering and mechanics of large amyloid fibers, MESA, and genetically encoded 3D printing (GET-Print).
Polymer Processing. Our research group specializes in biopolymer compounding. We continue to pursue the creation of new biopolymers for use in commodity plastics applications like packaging and automobile parts. Typical polymer processing involves synthesis, compounding, and molding. Biopolymers are synthesized in water at low temperature and atmospheric pressure. Typical fossil fuel based polymers are synthesized in organic solvent and/or at very high temperature and pressure. Both are compounded and molded but biopolymers are compounded and molded at much lower temperature. The Renewable Materials Research Group is researching ways to utilize polymer relaxation processes (Scheme 2) to bend large-scale polymer components, thus eliminating the costly molding step. “Shape morphing” is a bioinspired approach to polymer processing where extruded sheets can be induced to bend into a shape like a tree trunk or feather quill. The induced curvature can occur with a very low energy stimulus like sunlight or a relative humidity change. “Shape morphing” involves creating spatially heterogeneous biopolymers that can respond to a stimulus.
The Renewable Materials Research Group is part of the Biomolecular Engineering Cluster at Virginia Tech, which includes the Biofuels and Carbohydrates Laboratory , Metabolic Engineering and Systems Biology Laboratory , Ruder Research Group , and Zhang Research Group .
(* undergraduate student, ** graduate student, *** post-doc)