Advanced titanium dioxide-polytetrafluorethylene (TiO2-PTFE) nanocomposite coatings on stainless steel surfaces with antibacterial and anti-corrosion properties

Highlights: • TiO₂-PTFE coatings were prepared via a sol-gel process using PDA as an intermediate layer • The PDA layer improved adhesion strength and uniformity of the coating • The TiO₂-PTFE coating demonstrated significant antibacterial activity, corrosion resistance and biocompatibility -- Abstract: Bacterial infection and corrosion are two of the most common causes of the failure for the use of biomedical metallic implants. In this paper, we developed a facile two-step approach for synthesizing a TiO₂-PTFE nanocomposite coating on stainless steel substrate with both antibacterial and anticorrosion properties by using a sol-gel dip coating technique. A sub-layer of bioinspired polydopamine (PDA) was first coated on the stainless steel substrate to improve the adhesion and reactivity, then TiO₂-PTFE was uniformly co-deposited onto the PDA sub-layer. Both PTFE and TiO₂ contents had a significant influence on the surface energy of the TiO₂-PTFE coating. The coating with the total surface energy of 26 mJ/m² exhibited minimal bacterial adhesion against both Gram-negative Escherichia coli WT F1693 and Gram-positive Staphylococcus aureus F1557, which was explained using the extended DLVO theory. Benefiting from the synergistic effect between TiO₂ and PTFE, the TiO₂-PTFE coating showed improved corrosion resistance in artificial body fluids compared with the sole TiO₂ coating or PTFE coating. The TiO2-PTFE coating also demonstrated extraordinary biocompatibility with fibroblast cells in culture, making it a prospective strategy to overcome current challenges in the use of metallic implants.