No abstract

Natural articular cartilages exhibit extraordinary lubricating properties and excellent load-bearing capacity based on their penetrated surface lubricated biomacromolecules and gradient-oriented hierarchical structure. Hydrogels are considered as the most promising cartilage replacement materials due to their excellent flexibility, good biocompatibility, and low friction coefficient. However, the construction of high-strength, lowfriction hydrogels to mimic cartilage is still a great challenge. Here, inspired by the structure and functions of natural articular cartilage, anisotropic hydrogels with horizontal and vertical orientation structure were constructed layer by layer and bonded with each other, successfully developing a bilayer oriented heterogeneous hydrogel with a high load-bearing capacity, low friction, and excellent fatigue resistance. The bilayer hydrogel exhibited a high compressive strength of 5.21 ± 0.45 MPa and a compressive modulus of 4.06 ± 0.31 MPa due to the enhancement mechanism of the anisotropic structure within the bottom anisotropic hydrogel. Moreover, based on the synergistic effect of the high load-bearing capacity of the bottom layer and the lubrication of the surface layer, the bilayer hydrogel possesses excellent biotribological properties in hard/soft (0.032) and soft/soft (0.028) contact, which is close to that of natural cartilage. It is worth noting that the bilayer oriented heterogeneous hydrogel is able to withstand repeated loading without fatigue crack. Therefore, this work could open up a new avenue for constructing cartilage-like materials with both high strength and low friction.

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.

No abstract

No abstract