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Natural articular cartilage has excellent superlubrication property, and it is attributed to the hydration lubrication mechanism of the charged biomacromolecules which extend from the cartilage surface to form a brush‐like layer. In this study, a bioinspired brush‐like polyelectrolyte, namely poly(2‐methacryloyloxyethyl phosphorylcholine) (PMPC), is grafted onto the SiO2 wafer and polystyrene (PS) microsphere via surface‐initiated polymerization to enhance the lubrication performance. The characterization of Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, water contact angle, and scanning electron microscopy demonstrates that the PMPC polymer brushes are successfully modified onto the substrates. Furthermore, the lubrication test performed using atomic force microscope, with the PMPC‐grafted SiO2 wafer and PMPC‐grafted PS microsphere as the contact tribopair, shows that the PMPC‐functionalized surfaces significantly reduce friction coefficient under different test conditions. The tenacious water hydration shells formed surrounding the zwitterionic charges of PMPC polymer brushes are responsible for the reduced friction coefficient, which could support high pressures without being squeezed out under loading. In summary, the articular cartilage‐inspired surface functionalization method can be used to modify various substrates for enhanced lubrication.

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Titanium and its alloys have long been used as implantable biomaterials in orthopedics; however, to the best of our knowledge, few studies were reported to investigate surface functionalization of titanium for enhanced lubrication and sustained drug release. In the present study, titania nanotube arrays (TNTs) were prepared by anodization as effective drug nanocarriers, using titanium as the substrate. Meanwhile, motivated by articular cartilage-inspired superlubricity and mussel-inspired adhesion, a copolymer containing both dopamine methacrylamide and 2-methacryloyloxyethyl phosphorylcholine was synthesized (DMA−MPC) and spontaneously grafted onto the TNT surface, which was validated by characterization techniques such as scanning electron microscopy, water contact angle measurements, and X-ray photoelectron spectroscopy. Additionally, the lubrication test showed that copolymer-grafted TNTs have remarkably reduced friction coefficients compared with bare TNTs. Furthermore, the drug release test demonstrated that copolymer-grafted TNTs inhibited burst drug release and achieved sustained drug release in comparison with bare TNTs. In conclusion, the bioinspired surface functionalization strategy developed here, namely DMA−MPC copolymer-grafted TNTs, can be applied to modify orthopedic biomaterials (such as titanium) for enhanced lubrication and sustained drug release.

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