Self-assembly of globular protein-polymer diblock copolymers and globular protein-structural protein diblock copolymers provides a direct route towards nanopatterning proteins and enzymes at high densities while also preserving high levels of protein activity. By effectively nanopatterning proteins, this technique has the potential to aid in the fabrication of a variety of highly efficient biocatalytic, bioelectronic and biosensor devices. Our globular protein-polymer block copolymers are synthesized by covalently attaching a single monodisperse polymer to each protein molecule using site-specific chemistry. In contrast, our globular protein-structural protein block copolymers are synthesized in a single step, using E. Coli, with the joining of the two protein blocks occurring at the genetic level—by employing genetic engineering, the DNA that encodes for the globular and structural blocks can be joined together. Self-assembly of these materials is typically induced through solvent evaporation. We utilize a combination of scattering and microscopy techniques to investigate the resulting self-assembled nanostructures in solution, bulk, and thin film samples. The phase behavior of these materials is studied as a function of a wide variety of factors, including relative polymer volume fraction, block copolymer concentration in solution, diblock and triblock architectures, globular protein shape and orientation, and temperature. Investigation of these different factors has resulted in a rich variety of structures including cylinders, lamellae, perforated lamellae and disordered micelles.
Within this project area, we are continually exploring the incorporation of new proteins, including enzymes and antibodies, and polymers into our materials to demonstrate the utility of this approach for nanopatterning a wide range of commercial and scientific applications. In fact, the range of potential applications is limited only by the number of different enzymatically catalyzed reactions. By tuning the chemistry of the polymer/structural protein block, control may be achieved over the type of nanostructure formed and transport properties through materials can potentially be engineered. While the incorporation of new proteins or polymers will expand the functionality of such devices, it will also alter the solvent mediated interactions driving self-assembly. We are interested in exploring such effects as globular protein surface chemistry and globular protein shape and identity on the self-assembly behavior of these types of materials and on developing thermodynamic models for the complex self-assembly process in globular protein-polymer conjugates and globular protein-structural protein fusions.