Self-Assembly of Fusion Proteins to Form Biofunctional Materials

Enzyme-functionalized polymeric materials have attracted increasing attention for applications in biomedical materials, sensing, biocatalysis, energy conversion, and chemical agent detoxification, where controlling the nanostructure of the functional proteins can enable advances in material performance. Block copolymer self-assembly is an elegant solution to control protein structure on the 5-50 nm length scale, and the folded shapes and specific interactions of the protein blocks lead to rich new phase behavior. This proposal will investigate the potential of fusion proteins to direct the self-assembly of globular proteins in a manner analogous to diblock copolymers. The use of fusion proteins will enable the easy preparation of site-specific conjugates, using genetic engineering to control molecular structure. The thermodynamics of globular-coil protein blends will be explored to understand how the sequence of a coillike protein affects its miscibility with globular proteins, allowing a set of proteins with potential for directing self-assembly to be identified. Fusion proteins will then be cloned from target globular proteins and promising coil protein sequences in order to produce protein block copolymer molecules capable of self-assembly.

Processing methods to produce nanostructured gels and plastics from aqueous casting will be developed, and the resulting self-assembled materials will be characterized to identify the type of nanostructures formed. Spectroscopic methods and activity assays will be used to assess protein fold and function within the nanomaterials. Comparison to coarse-grained theories for protein/polymer solutions and protein-polymer conjugate self-assembly will enable the universal thermodynamics of self-assembly for globular-coil protein fusions to be elucidated. The complex challenges of understanding how protein fold and specific interactions affect nanostructuring in soft materials is an emerging obstacle in materials science that must be addressed to further advance knowledge and application of bio-based materials. These fundamental studies of globular protein-coil protein fusion self-assembly will provide both a new method for material preparation and an understanding of the materials science and thermodynamics of these complex systems.

This proposal will expand the application of protein-based materials by enabling control over self-assembled nanostructure formation using fusion proteins prepared by relatively easy and inexpensive synthesis and purification methods. A diverse team of graduate and undergraduate researchers will perform research on this project, providing valuable training experiences to engineers at several educational levels. This research focus on biologically-based materials will be integrated with efforts to develop novel methods that will impact both undergraduate and high school teaching. A new pedagogy will be developed for teaching the introductory Chemical Engineering course, integrating the study of materials research and product development that reflects the modern scope of the profession. The undergraduate level educational objectives of this proposal transform the teaching of the universally accepted introductory chemical engineering course, impacting education in this discipline worldwide. In collaboration with local high school teachers, teaching materials for a unit on sustainable polymers and biomaterials and demonstrations of polymer materials will also be developed to translate excitement about this research area to secondary school students. A high school pedagogy that integrates sustainable polymer materials research to teach core requirements of state and national science education standards will provide an easily adopted forum for the broad dissemination of this research.