Patterning Functional Proteins in Ultrabithorax-Based Materials

The ability to add bioactivities, such as cell signaling or ligand recognition, to biomaterials has generated the potential to include multiple bioactivities into a single material. In some cases, it is desirable to localize these activities to different areas of the biomaterial, creating functional patterns. While photolithography and 3D printing have been effective techniques for patterning functions in many materials, patterning remains a challenge in materials composed of protein, in part due to how these materials are artificially assembled. Protein fibers are often produced from protein films that co-acervate at the air-water interface. This chapter describes methods to leverage this coacervation process to pattern materials, using the Drosophila melanogaster Hox protein Ultrabithorax (Ubx) as a model self-assembling protein. Through gene fusion, Ubx and a functional protein are produced as a single polypeptide, capable of both forming materials and performing the activity of interest. This functionality is retained in the final materials. In this chapter, we describe how to use multiple Ubx fusion proteins to not only imbue the final materials with multiple functions, but also to create macroscale patterns of the appended proteins in fibrous protein-based materials. These patterned materials include striped fibers, bifunctional-faced fibers, gradient fibers, and core-shell fibers.