Strong Bioinspired Polymer Hydrogel with Tunable Stiffness and Toughness for Mimicking the Extracellular Matrix

Inspired by the delicate architecture of hyaline articular cartilage, we report on a biomimetic polymer hydrogel that incorporates strong intermolecular hydrogen bonding between urethane-urethane linkages as well as urethane-ester linkages. The resultant hydrogel, containing ≈75% water, can endure a compressive stress up to 56 MPa with a strain of 98%, and exhibit tunable compressive modulus (0.19-1.38 MPa), as well as toughness (3629-28290 J m^-2) within a wide range. The tensile strength and elastic modulus reach as high as 0.56 and 5.5 MPa, respectively. The high stiffness and toughness enable the gel to withstand cyclic compressive loadings without fracturing. Moreover, our hydrogel mimics the extracellular matrices of cartilage and bone tissues and provides biochemical and physical cues that support the three-dimensional proliferation of chondrocytes and osteogenic differentiation of preosteoblasts.