X-ray and UV Irradiation-Induced Reactive Oxygen Species Mediated Antibacterial Activity in Fe and Pt Nanoparticle-Decorated Si-Doped TiCaCON Films

Abstract

Bone implants with biocompatibility and the ability to biomineralize and suppress infection are in high demand. The occurrence of early infections after implant placement often leads to repeated surgical treatment due to the ineffectiveness of antibiotic therapy. Therefore, an extremely attractive solution to this problem would be the ability to initiate bacterial protection of the implant by an external influence. Here, we present a proof-of-concept study based on the generation of reactive oxygen species (ROS) by the implant surface in response to X-ray irradiation, including through a layer of 3 mm adipose tissue, providing bactericidal protection. The effect of UV and X-ray irradiation of the implant surface on the ROS formation and the associated bactericidal activity was compared. The focus of our study was light-sensitive Si-doped TiCaCON films decorated with Fe and Pt nanoparticles (NPs) with photoinduced antibacterial activity mediated by ROS. In the visible and infrared range of 300−1600 nm, the films absorb more than 60% of the incident light. The high light absorption capacity of TiO 2 /TiC and TiO 2 /TiN heterostructures was demonstrated by density functional theory calculations. After short-term (5−10 s) low-dose X-ray irradiation, the films generated significantly more ROS than after UV illumination for 1 h. The Fe/TiCaCON-Si films showed enhanced biomineralization capacity, superior cytocompatibility, and excellent antibacterial activity against multidrug-resistant hospital Escherichia coli U20 and K261 strains and methicillin-resistant Staphylococcus aureus MW2 strain. Our study clearly demonstrates that oxidized Fe NPs are a promising alternative to the widely used Ag NPs in antibacterial coatings, and X-rays can potentially be used in ROS-regulating therapy to suppress inflammation in case of postimplant complications.

Synergistic Bactericidal Effect of Zn2+ Ions and Reactive Oxygen Species Generated in Response to Either UV or X-ray Irradiation of Zn-Doped Plasma Electrolytic Oxidation TiO2 Coatings

“…It was previously shown that the surface of Cu-doped PEO coatings generates ROS after UV irradiation . A comparison of the effects of UV and X-ray irradiation on the surface of metal nanoparticles-decorated TiCaCON–Si coating showed that the maximum ROS concentration after short-term soft X-ray irradiation was significantly higher than after long-term UV irradiation . The effect of X-ray irradiation on ROS generation by the PEO surface has not been studied previously.…”

“…These changes in the band structure affect the material photochemical properties, promote the indirect transfer of electrons from the valence band to the conduction band, and prevent rapid charge recombination . X-ray irradiation-induced ROS-mediated antibacterial activity was recently reported for metal nanoparticles-decorated TiCaCON–Si films, but for the PEO coating, it is observed for the first time. In conclusion, we would like to highlight the important difference between our experiments, in which PEO-Zn coatings were exposed to UV and X-ray irradiation before being placed in cell culture, compared to UV irradiation of an Ag-containing Ti sample simultaneously with bacteria, which resulted in an enhanced bactericidal effect due to hydroxyl radicals generated from the bacterial cell .…”

“…Recently, the X-ray irradiation-induced ROS-mediated antibacterial activity was reported in the Fe and Pt nanoparticle-decorated TiCON-based films . Importantly, the maximum ROS concentration after X-ray irradiation was several times higher than after UV illumination, which paves a new avenue to combat infection.…”