Cu-CDs drive the formation of protein tribo-film on the porous UHMWPE to achieve auto-antifriction property in BSA solution

Ultra-high-molecular weight polyethylene (UHMWPE) is the most widely used friction material for artificial joints. Polyethylene debris generated during its use is the main reason behind the aseptic loosening of artificial joints. Improving the wear resistance of UHMWPE and reducing debris generation have been the focus of research in this field. Inspired by the structure of natural cartilage and based on our previous research, we developed a new type of porous UHMWPE-based artificial joint material doped with copper-containing carbon dots (Cu-CDs). In a protein-containing lubricating medium, this material exhibited auto-antifriction properties by absorbing/releasing the lubricating medium and forming a protein film on the tribo-interface. These effects can significantly enhance the wear resistance of UHMWPE. The results showed that spherical Cu-CDs with an average size of 5–6 nm were successfully prepared. The tensile strength of the porous UHMWPE doped with Cu-CDs (Cu-CDs@UHMWPE) (approximately 9.93 MPa) was close to that of natural joint cartilage. Cu-CDs@UHMWPE promoted the adsorption of proteins by the friction interface and formed a protein film that reduced wear. Under the same friction conditions, the wear index of Cu-CDs@UHMWPE was approximately three times lower than that of pure UHMWPE. This study showed that UHMWPE can be imbued with the ability to form protein films to enhance wear resistance, and these findings provide experimental and theoretical evidence for the development of novel biomimetic artificial joint materials.