The design of advanced multifunctional Mg-based bone implants with enhanced corrosion resistance, antibacterial, and osteogenic activities should be brought to the forefront to fulfill the requirement of clinical medicine. In this work, a PEO/Mg–Zn–Al layered double hydroxide (LDH) composite coating on Mg alloy was developed via plasma electrolytic oxidation (PEO) and hydrothermal treatment. The porous structure formed during the PEO process was filled by Mg–Zn–Al LDH. The as-prepared coating exhibited better corrosion resistance than the PEO/Mg–Al LDH composite coating. In addition, the composite coating showed strong antimicrobial ability against Gram-positive Staphylococcus aureus, which was attributed to the release of Zn ions. When Zn content was controlled at 1.17 at% in the composite coating, rBMSCs showed long-term cytocompatibility and enhanced initial adhesion. Moreover, with the synergistic functions of Zn and Mg ions, cells on the composite coating showed a higher level of alkaline phosphatase activity and expression of osteopontin (OPN). With enhanced corrosion resistance, antibacterial, and osteogenic differentiation abilities, the PEO/Mg–Zn–Al LDH composite coating exhibits a promising application in bone-related implants.

Summary Antibiotics have been considered as effective weapons against bacterial infections since they were discovered. However, antibiotic resistance caused by overuse and abuse of antibiotics is an emerging public health threat nowadays. Fully defeating bacterial infections has become a tough challenge. In this work, cerium oxide was fabricated on medical titanium by thermolysis of cerium-containing metal-organic framework (Ce-BTC). Regulation of Ce (Ⅲ)/Ce (Ⅳ) ratios was realized by pyrolysis of Ce-BTC in different gas environment, and the antibacterial properties were studied. The results indicated that, in acidic conditions, ceria with a high Ce (Ⅲ)/Ce (Ⅳ) ratio owned high oxidase-like activity which could produce reactive oxygen species. Moreover, ceria with high Ce (Ⅲ) content possessed strong ATP deprivation capacity which could cut off the energy supply of bacteria. Based on this, ceria with a high Ce (Ⅲ)/Ce (Ⅳ) ratio exhibited superior antibacterial activity

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Intelligent control of the immune response is essential for obtaining percutaneous implants with good sterilization and tissue repair abilities. In this study, polypyrrole (Ppy) nanoparticles enveloping a 3D frame of sulfonated polyether ether ketone (SP) surface are constructed, which enhance the surface modulus and hardness of the sulfonated layer by forming a cooperative structure of simulated reinforced concrete and exhibit a superior photothermal effect. Ppy-coated SP could quickly accumulate heat on the surface by responding to 808 nm near-infrared (NIR) light, thereby killing bacteria, and destroying biofilms. Under NIR stimulation, the phagocytosis and M1 activation of macrophages cultured on Ppy-coated SP are enhanced by activating complement 3 and its receptor, CD11b. Phagocytosis and M1 activation are impaired along with abolishment of NIR stimulation in the Ppy-coated SP group, which is favorable for tissue repair. Ppy-coated SP promotes Collagen-I, vascular endothelial growth factor, connective tissue growth factor, and 𝜶-actin (Acta2) expression by inducing M2 polarization owing to its higher surface modulus. Overall, Ppy-coated SP with enhanced mechanical properties could be a good candidate for clinical percutaneous implants through on-off phagocytosis and switchable macrophage activation stimulated with NIR.

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