(647i) Stimuli-Responsive Assembly from Biosynthetic Coiled-Coil Peptide Building Blocks for the Construction of Nanomaterials with Programmed Architectures

Nature provides exquisite control of material properties from the bottom up, where the underlying amino acid sequence of proteins give rise to hierarchical nanostructures and related micro- to macro-scale material properties. Examples of this precision range from viral particles to extracellular matrix bottlebrushes. However, the architectural complexity of many hierarchical nanostructures found in nature has made it difficult for scientists to replicate with synthetic building blocks. To address this, we have combined molecular engineering principles with biosynthetic techniques to create coiled-coil peptides as building blocks, known as bundlemers. Bundlemers are computationally designed to possess robust stability and modularity, allowing tailored modifications of residues for hierarchical assembly. Through click and enzymatic chemistry, we can construct these bundlemers into precise protein-like nanostructures with programmable functionalities. By integrating an unnatural amino acid, we used copper-catalyzed azide-alkyne cycloaddition (CuAAC) to attach the pH-responsive peptides responsible for the assembly of rod-like polymer backbone. Further, sortase ligation, which is facilitated by an enzyme and exhibits high reaction efficiency similar to traditional click chemistries, was employed to attach pendant groups, or complementary bundlemer peptides, onto the assembled backbone. We demonstrate approaches of the synthesis and controlled formation of assembled units with programmed structure and responsiveness, providing opportunities for the construction of bottlebrush nanostructures through the manipulation of the grafted peptide sequence and alteration of the reaction conditions. This work establishes design rules and workflows for the creation of hierarchically-structured, proteinaceous nanomaterials. By demonstrating controlled synthesis and structure formation, we lay the foundation for the construction of previously inaccessible protein-based structures relevant for a range of applications, from biolubricants mimicking naturally occurring aggrecan in the human joints, to targeted drug delivery vehicles for dense tissue such as the brain.