Fig. 3: Hydrogels made of metal ion-clad picot fibres.

a Photographs of the PAM (top), p-Pep (middle) and p-Pep/Cu²⁺ (bottom) hydrogels under compression-relaxation cycles. The PAM and p-Pep hydrogels fractured at strains of 80 and 90%, whereas the p-Pep/Cu²⁺ hydrogel almost fully recovered from a strain of 90%. Scale bar = 5 mm. b Photographs of a p-Pep/Cu²⁺ hydrogel compressed with a sharp blade and allowed to relax. No detectable cut was observed on the gel after the release of compression. Scale bar = 5 mm. c Photographs of the original, stretched (strain = 23 mm mm⁻¹) and fractured p-Pep/Cu²⁺ hydrogel. The original width and length of the sample between the clamps were 8 and 1 mm, respectively. Scale bar = 5 mm. For a–c, the peptide concentration in the precursors of the p-Pep and p-Pep/Cu²⁺ hydrogels was 6% w/v.