Fig. 1: Bioinspired design of fatigue-resistant hydrogel adhesion.

a Schematic illustration of the fatigue-resistant adhesions between soft connective tissues (cartilage, tendon, and ligament) and bones. b The transitional interface from uncalcified collagen nanofibrils (i) to calcified nanofibers (ii) to the bone (iii). The nanostructured composites of aligned collagen nanofibrils and ordered hydroxyapatite nanocrystals contribute to the fatigue-resistant adhesions of the cartilages, tendons, and ligaments to the bones. c Bioinspired fatigue-resistant adhesion of synthetic hydrogels by anchoring ordered high-energy nanostructures (e.g., nanocrystalline domains) on engineering materials. These high-energy nanostructures (e.g., nanocrystalline domains) can effectively pin the crack propagation both at the interface and within the bulk hydrogels, since they require a much higher energy for fatigue-crack propagation than the corresponding amorphous polymer chains. d Fatigue-resistant adhesion of poly(vinyl alcohol) (PVA) hydrogel to substrates through the anchorage of ordered nanocrystalline domains on the substrates with hydrogen bonds.