Visible-Light-Induced Photocatalytic and Antibacterial Activity of TiO₂ Codoped with Nitrogen and Bismuth: New Perspectives to Control Implant-Biofilm-Related Diseases

Abstract

Biofilm-associated diseases are one of the main causes of implant failure. Currently, the development of implant surface treatment goes beyond the osseointegration process and focuses on the creation of surfaces with antimicrobial action and with the possibility to be re-activated (i.e., light source activation). Titanium dioxide (TiO2), an excellent photocatalyst used for photocatalytic antibacterial applications, could be a great alternative, but its efficiency is limited to the ultraviolet (UV) range of the electromagnetic spectrum. Since UV radiation has carcinogenic potential, we created a functional TiO2 coating codoped with nitrogen and bismuth via the plasma electrolytic oxidation (PEO) of titanium to achieve an antibacterial effect under visible light with re-activation potential. A complex surface topography was demonstrated by scanning electron microscopy and three-dimensional confocal laser scanning microscopy. Additionally, PEO-treated surfaces showed greater hydrophilicity and albumin adsorption compared to control, untreated titanium. Bismuth incorporation shifted the band gap of TiO2 to the visible region and facilitated higher degradation of methyl orange (MO) in the dark, with a greater reduction in the concentration of MO after visible-light irradiation even after 72 h of aging. These results were consistent with the in vitro antibacterial effect, where samples with nitrogen and bismuth in their composition showed the greatest bacterial reduction after 24 h of dual-species biofilm formation (Streptococcus sanguinis and Actinomyces naeslundii) in darkness with a superior effect at 30 min of visible-light irradiation. In addition, such a coating presents reusable photocatalytic potential and good biocompatibility by presenting a noncytotoxicity effect on human gingival fibroblast cells. Therefore, nitrogen and bismuth incorporation into TiO2 via PEO can be considered a promising alternative for dental implant application with antibacterial properties in darkness, with a stronger effect after visible-light application.

Comparison between Plasma Electrolytic Oxidation Coating and Sandblasted Acid-Etched Surface Treatment: Histometric, Tomographic, and Expression Levels of Osteoclastogenic Factors in Osteoporotic Rats

“…Thus, the PEO surface coating was shown to be extremely promising and offered excellent performance in terms of bone repair, as demonstrated in the present study. This surface coating also has superior mechanical [2,17,18] and antimicrobial parameters [21,22,45]. Given the investigations into the favorable structural properties of the PEO surfaces of implants, which were corroborated in the present study by the biological responses of the bone-implant interface, we believe that the next steps include industrial production for human clinical studies.…”

Visible Light-Enhanced Antibacterial and Osteogenic Functionality of Au and Pt Nanoparticles Deposited on TiO2 Nanotubes

“…However, it is difficult to overcome antibiotic resistance, side effects, and limitations of single use. Recently, alternative treatments without antibacterial agents, such as antimicrobial polymers [8], antibacterial Ag nanoparticles (NPs) [9,10], photodynamic therapy [11], and photocatalysis of titania (TiO 2 ) [12][13][14] have been introduced due to increased multi-drug resistance of bacterial strains. Among these treatments, the photocatalytic antibacterial effect of TiO 2 is expected to be very useful, since dental implants and medical implantable devices mainly use titania or titania alloy.…”

“…There have been many reports of additive doping to extend the limited photocatalytic effect of titania in the ultraviolet to visible light region [12,[15][16][17]. Especially, the combination of noble metals (gold or platinum, Au or Pt, respectively), which have excellent biological compatibility, and TiO 2 has been reported to show remarkable visible light photocatalytic activity [18][19][20][21][22].…”

<p>Biomedical Applications of TiO₂ Nanostructures: Recent Advances</p>

“…However, recent studies have solved this problem by using visible light-activated photocatalysts, like Ag/AgBr/TiO 2 , and doped-TiO 2 nanostructures. [51][52][53] The first use of TiO 2 as a photocatalytic micro biocide was reported by Matsunaga et al (1985), when they investigated TiO 2 antibacterial activity towards Lactobacillus acidophilus, Saccharomyces cerevisiae and E. coli. 54 Various studies have explained that the photocatalytic activity of TiO 2 in water is efficient against broad range of organisms, such as bacteria (Gram-negative and Gram-positive), fungi, viruses, algae, protozoa and bacterial toxins.…”