Biological Materials Processing: Time-Tested Tricks for Sustainable Fiber Fabrication

Abstract

There is an urgent need to improve the sustainability of the materials we produce and use. Here, we explore what humans can learn from nature about how to sustainably fabricate polymeric fibers with excellent material properties by reviewing the physical and chemical aspects of materials processing distilled from diverse model systems, including spider silk, mussel byssus, velvet worm slime, hagfish slime, and mistletoe viscin. We identify common and divergent strategies, highlighting the potential for bioinspired design and technology transfer. Despite the diversity of the biopolymeric fibers surveyed, we identify several common strategies across multiple systems, including: (1) use of stimuliresponsive biomolecular building blocks, (2) use of concentrated fluid precursor phases (e.g., coacervates and liquid crystals) stored under controlled chemical conditions, and (3) use of chemical (pH, salt concentration, redox chemistry) and physical (mechanical shear, extensional flow) stimuli to trigger the transition from fluid precursor to solid material. Importantly, because these materials largely form and function outside of the body of the organisms, these principles can more easily be transferred for bioinspired design in synthetic systems. We end the review by discussing ongoing efforts and challenges to mimic biological model systems, with a particular focus on artificial spider silks and mussel-inspired materials.

A Minispidroin Guides the Molecular Design for Cellular Condensation Mechanisms in S. cerevisiae

“…In the spider silk gland, the assembly of spidroins into fibrillar structures is triggered by exposure to low pH at around 5 to 5.5. ,, Therefore, we tested the response of intracellular NT2RepCT to different pH values. 2,4-Dinitrophenol (DNP) (2 mM) was used together with buffers to change intracellular pH.…”

Protein-Based Biological Materials: Molecular Design and Artificial Production

“…There are several challenges ahead before artificial materials replicating the model systems described in this review can become a reality in daily life applications. The spatiotemporal pathways by which biology precisely regulates molecular assembly from the cellular level to the final, multi-scale material structure are still largely unknown with a few exceptions such as silk fibers and mussel threads, for which breakthroughs in our understanding of their biofabrication have been achieved in recent years (see Rising and Harrington in this thematic issue 639 ). The role of many PTMs also remains elusive in many model systems.…”

Coacervate Phase Evolution and Membrane Formation in Natural Seawater

“…Conventional processing of engineering polymers relies on thermal heating or organic solvents dissolving, such as the preparation of porous polymer membranes via thermally induced or nonsolvent induced phase separations . In stark contrast, living organisms sustainably produce a variety of materials under ambient temperatures and in aqueous environments. − Condensed materials made by marine organisms have been under particular scrutiny in recent years. Covering 70% of the earth’s surface, oceans are likely to experience increased human activity; thus, it is both a scientific curiosity and a technological imperative to advance sustainable polymer processing in saline media.…”