Collaborative Research: DMREF: De Novo Proteins as Junctions in Polymer Networks

Non-technical Description: Nature uses proteins to create biomaterials that range from spider silk to human tissue. Synthetic materials that utilize proteins have potential as biodegradable plastics and composites (protein-polymer networks). It is critical to understand the protein design parameters that determine the desired material outcomes in protein-polymer networks. In addition to protein structure, the topology of the polymer network serves an important role in the mechanical response of these materials. While the mechanical properties of these materials can be experimentally determined, computational simulations can provide critical insights into the mechanical response of proteins as they unfold within a network structure. The transformative scientific aspects of our proposal are (i) the synthesis and computational simulations of de novo designed proteins and their respective protein-polymer networks and (ii) techniques for mechanical characterization of polymer-protein networks on the microscale that will accelerate the discovery and deployment of proteins as junctions in polymer networks for biohybrid plastics and engineering bioplastics. Additionally, 3D printing will enable the distributed manufacturing of parts, as well as custom designs that can be created by architects, engineers, and other users. This project addresses the national need for advanced manufacturing methods that are more sustainable built environments via reduced carbon footprint (reduced transport costs and greener production) and chemical circularity (chemical recycling of protein-based materials). This project also addresses the national need to develop the next generation of a highly skilled and diverse future workforce. Technical Description: The central objective of this proposal is to elucidate the design principles for de novo designed proteins as mechano-responsive junctions in protein-polymer networks. The convergence of computational de novo protein design and materials science presents a unique opportunity to create protein-based thermosets that are superior to conventional synthetic materials. The structure and composition of designed proteins can be optimized to control the processability of the proteins (via additive manufacturing) and the bulk mechanical properties of the materials. In particular, proteins can serve as mechanophores that respond to extrinsic mechanical forces to release their stored length. The factors that determine the stored length include the nominal length of the outstretched protein, the number of strands per protein junction and the force required to mechanically unfold the protein. The topology of the protein-polymer network also serves an important role in the mechanical response of these materials. While the mechanical properties of these materials can be experimentally determined, computational simulations can provide critical insights into proteins unfolding and refolding in a network and ultimately accelerate the discovery of proteins for advanced materials. This DMREF project will (i) develop de novo designed proteins that can be readily transformed into junctions within polymer networks, (ii) investigate de novo designed proteins as mechano-responsive junctions that unfold within networks, and (iii) demonstrate the additive manufacturing of intelligent protein-polymer networks that remodel via protein unfolding and refolding. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.