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.
Highlights
Metallic implants are engineered systems designed to provide internal support to biological tissues and have been used extensively in dental, endovascular and orthopaedic surgery [1,2]
In a typical sol-gel TiO2 coating process, the formation of crystalline anatase TiO2 usually requires calcination at over 400 °C [39], but this temperature is much higher than the glass-transition temperature (Tg) and melting point of PTFE [40]
To synthesise coatings with photocatalytic activity, a range of anatase TiO2 nanoparticles was incorporated into the sol and the TiO2-PTFE coatings were heat treated at 100 °C (Fig. 1a)
Summary
Metallic implants are engineered systems designed to provide internal support to biological tissues and have been used extensively in dental, endovascular and orthopaedic surgery [1,2]. Despite extensive local tissue debridement and prolonged systemic and targeted local antimicrobial therapy, the infected device often must be removed to fully resolve the problem [5]. Current strategies for preventing infections include coating or impregnating antibacterial agents such as antibiotics [6], nano‐silver [7] and other antiseptics [8,9] onto the implant surface. Most of these attempts fail to deliver sustained antibacterial effects as the coatings are prone to loss of activity after covalent bonding [10]. Microbes being exposed to sub-lethal levels of the antimicrobials may trigger the emergence of resistance in situ
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