Bioengineered Protein Fibers with Anti-Freezing Mechanical Behaviors

Most biological protein fibers exhibit extraordinary mechanical performance at room temperatures but inferior freezing resistance. Maintaining fiber's high strength and toughness under subzero conditions remains a great challenge. Herein, a class of freezing tolerant protein fibers is reported with favorable ice-phobic capacity and cryogenic mechanical performance by genetic engineering. Inspired by nature, chimeric recombinant proteins consist of highly ordered structural protein domains and antifreeze protein (AFP) modules, showing excellent ice recrystallization inhibition activity. Such features endow the resulting protein fibers with remarkable mechanical properties and good mechanical stability in subzero environments. In stark contrast to conventional fibers, the engineered protein fibers maintain high cryogenic stiffness and toughness even at −20 and −40 °C. The synergistic contribution of structural protein and AFP plays an important role for the extraordinary anti-freezing mechanical behaviors. Thus, this study pioneers an engineering approach for the next generation of biological fibers with tailored applications in extreme settings.