Antibacterial and surface properties of post-light-activated metal-free phthalocyanine-deposited TiO2 nanotube smart surfaces

Abstract

The utilisation of implantable medical devices has become safer and more prevalent since the establishment of sterilisation methods and techniques a century ago. Nevertheless, device-associated infections remain a significant and growing concern, particularly in light of the continued rise in the number of medical device implantations. This underscores the imperative for the development of efficacious prevention and treatment strategies for device-associated infections, as well as further investigation into the design of innovative antibacterial surfaces for medical device applications. The motivation of this work is to investigate the post-light-activated antibacterial photosensitive surfaces fabricated on medical titanium (Ti) surfaces. Thus, in this work, metal-free phthalocyanine (H₂Pc)-deposited TiO₂ nanotube (TNT) array smart photosensitive surfaces were fabricated on titanium (Ti) surfaces for medical device applications. First, well-ordered nanotube surfaces were produced on titanium using an anodic oxidation (AO) process. Then, H₂Pc was accumulated onto TNT surfaces using a physical vapour deposition (PVD-TE) process. H₂Pc-deposited TNT surfaces were fabricated on Ti substrates by combining AO and physical vapour deposition (PVD-TE) processes in this work for the first time in the literature. H₂Pc was largely coated onto TNT arrays and exhibited elemental homogeneity throughout the whole surface. The contact angle of H₂Pc-deposited TNT surfaces was about 89° whereas other Ti and TNT surfaces demonstrated hydrophilic characteristics. Therefore, they exhibited remarkable hydrophobic behavior in terms of antibacterial properties. Importantly, compared to Ti and TNT surfaces, the bacterial inhibition on sunlight-activated H₂Pc-deposited TNT surfaces was 94.9% for S. aureus and 97.3% for E. coli, respectively. According to these results, H₂Pc-deposited TNT innovative surfaces provided superior antibacterial activity post-light-activation under sunlight due to their photosensitive character.