Fabricating alginate fibers of high strength and toughness remains a great challenge because of the difficulty in improving both strength and toughness simultaneously. Herein, this work reported the hierarchical assembly of sodium alginate nano-helix and its potential application as a new reinforcing unit for alginate fibers. Contributed from the hierarchical structures of α-helix, β-sheet and tertiary helical alignment of nanofibrils, nano-helix improved the tensile strength of fibers with enhanced modulus, and prolonged elongation through unravelling the tertiary structures. Thus, the strength, elongation and toughness of alginate fibers were all enhanced by >200 %, solving the tradeoff of strength and toughness. The mechanical performance of nano-helix engineered alginate fibers is superior to present alginate fibers and even some other biomass-based fibers. The assembly of nano-helix provides a feasible reinforcing strategy for polysaccharide based materials, achieving simultaneous improvement of strength and toughness.

由于难以同时提高强度和韧性，制造具有高强度和韧性的海藻酸盐纤维仍然是一个巨大的挑战。在此，这项工作报道了海藻酸钠纳米螺旋的分层组装及其作为海藻酸盐纤维新增强单元的潜在应用。得益于纳米原纤维的α-螺旋、β-折叠和三级螺旋排列的分级结构，纳米螺旋提高了纤维的拉伸强度，提高了模量，并通过解开三级结构延长了伸长率。因此，海藻酸盐纤维的强度、伸长率和韧性均提高了 >200%，解决了强度和韧性的权衡问题。纳米螺旋工程藻酸盐纤维的机械性能优于目前的藻酸盐纤维，甚至是其他一些基于生物质的纤维。纳米螺旋的组装为多糖基材料提供了一种可行的增强策略，实现了强度和韧性的同时提高。