Fig. 1: Hydrogel design based on metal ion-clad picot fibres.

a Schematic of a conventional double-network hydrogel. The physically crosslinked network is designed to dissipate energy, and the covalently crosslinked network is used to provide hidden length. b Schematic of the hydrogel constructed by picot fibres made of self-assembling peptide strands with zipped flexible hidden lengths. Upon deformation of the hydrogel, the picot fibres are extended to dissipate energy efficiently and release the polyacrylamide hidden length without reducing the network connectivity of the hydrogels. c The peptide sequence and synthetic scheme for the metal ion-clad picot fibres. H2, H4, H6 and H10 correspond to four histidine residues at different positions of a GK₁₁ peptide. d The self-assembled structure of GK₁₁ (left) and a magnified region of this diagram showing the binding position of Cu²⁺ (right). The hydrogen bonds are shown as grey dashed lines. Histidine is coloured green in the ribbon representation in the left image and represented by sticks to illustrate the coordination bonds in the right image. A: H2, A: H4 and A: H6 correspond to three histidine residues in the N-terminal of a peptide and B: H10 corresponds to the histidine in the C-terminal of the neighbouring peptide.