Fabrication and Characterization of a Multilayer Hydrogel as a Candidate for Artificial Cartilage

Bone and cartilage are highly organized tissues with gradient layered, which makes cartilage have good lubrication and bearing capacity. Inspired by the gradient structure of natural articular cartilage, the PVA–HA and PVA–HA–PAA composite hydrogels were selected to prepare a hierarchical bionic cartilage material by physical bonding. The lower PVA–HA composite hydrogel and the upper PVA–HA–PAA composite hydrogel provide excellent lubrication and loading-bearing ability to bionic cartilage materials, respectively. Furthermore, the cartilage–bone material was constructed by grafting the multilayer bionic cartilage hydrogel onto the UHMWPE after oxidation esterification to simulate the bone–cartilage hierarchical structure. The multilayer cartilage material has excellent tensile fracture properties (tensile strength 38.90 ± 1.5 MPa, 545 ± 32%, tensile modulus 1.73 ± 0.06 MPa), compression properties (compressive strength 3.1 ± 0.15 MPa, compressive modulus 4.47 ± 0.2 MPa), thermostability, friction properties (friction coefficient 0.035 ± 0.0028), and biocompatibility. Thus, the bionic cartilage material has a gradient-layered structure with high strength and low friction, which significantly improves the stability and life of artificial joints.