Vapor-Responsive Shape-Memory Material Based on Carbon Nanotube Sponge Dominated by Pressure-Induced Conformational Transition of Spidroin

Spider silks, mainly constructed of spidroin, have received extensive attention for their excellent mechanical properties, slow bio-degradability, and high biocompatibility. However, due to uncontrollable protein-folding processes, the structural transition of spidroin, especially when composited with other functional materials under confinement, is insufficiently understood. Herein, we report a pressure-induced conformational transition process of the spidroin which is confined within carbon nanotube (CNT) sponge matrixes. The structural transition of spidroin from α-helix to β-sheet can be induced by a very small hydrostatic pressure (several megapascals) and recover easily through a subsequent solvent vapor annealing process in an ambient atmosphere. Therefore, the spidroin/CNT sponge exhibits reversible vapor-/pressure-sensitive “shape-memory” behavior with the recovery efficiency close to 100%. Our observation reveals a crucial mechanism for the conformational transition of spidroin under confinement, which paves the way toward the fabrication of spider silk-based products with superior performances.