Investigation of the in vitro photocatalytic antibacterial activity of nanocrystalline TiO₂ and coupled TiO₂/Ag containing copolymer on the surface of medical grade titanium

Abstract

Antibacterial surfaces have been in the focus of research for years, driven by an unmet clinical need to manage an increasing incidence of implant-associated infections. The use of silver has become a topic of interest because of its proven broad-spectrum antibacterial activity and track record as a coating agent of soft tissue implants and catheters. However, for the time being, the translation of these technological achievements for the improvement of the antibacterial property of hard tissue titanium (Ti) implants remains unsolved. In our study, we focused on the investigation of the photocatalysis mediated antibacterial activity of silver (Ag), and Ti nanoparticles instead of their pharmacological effects. We found that the photosensitisation of commercially pure titanium discs by coating them with an acrylate-based copolymer that embeds coupled Ag/Ti nanoparticles can initiate the photocatalytic decomposition of adsorbed S. salivarius after the irradiation with an ordinary visible light source. The clinical isolate of S. salivarius was characterised with MALDI-TOF mass spectrometer, while the multiplication of the bacteria on the surface of the discs was followed-up by MTT assay. Concerning practical relevance, the infected implant surfaces can be made accessible and irradiated by dental curing units with LED and plasma arc light sources, our research suggests that photocatalytic copolymer coating films may offer a promising solution for the improvement of the antibacterial properties of dental implants.

Mechanisms of the enhanced antibacterial effect of Ag-TiO2 coatings

“…Silver has been known as a broad-spectrum bactericide for centuries. It has been demonstrated that silver nanoparticle coatings on Ti based implants increased their biocompatibility and antibacterial properties (Gyorgyey et al 2016;Sulej-Chojnacka et al 2016). Titanium dioxide (TiO 2 ) has also been known as a broad-spectrum bactericide for a long time.…”

“…In addition, TiO 2 with moderate hardness and excellent resistance to wear and corrosion can significantly accelerate osteoblast cell growth and improve bone-forming functionality and direct the fate of stem cells in orthopedic-associated implants (Frandsen et al 2013;. This suggests that a Ag-TiO 2 nanocomposite coating may offer a promising solution for improvement of the antibacterial properties of dental and orthopedic implants (Cotolan et al 2016;Gyorgyey et al 2016). It has been reported that Ag-TiO 2 nanocomposite coatings exhibit a synergistic effect on antibacterial activity, which made their bactericidal activities stronger than Ag or TiO 2 coatings (Ashkarran et al 2011;Esfandiari et al 2014;Motlagh et al 2014;Prakash et al 2016).…”

TiO2/Ag–TiO2 Nanohybrid Films are Cytocompatible with Primary Epithelial Cells of Human Origin: An In Vitro Study

“…Two photocatalytic layers: 60 % TiO 2 / 40 % copolymer and 60% AgTiO 2 / 40 % copolymer ([Ag] = 0.001 m/m %) were investigated. We reduced the amount of nanosilver from 0.5 % to 0.001% compared to our previous experiments 26 . A hydrophilic polyacrylate resin [poly (ethyl-acrylate comethyl-methacrylate) (p(EA-co-MMA)) binder material (obtained from Evonik Industries, Germany) was used providing the polymer bed for TiO 2 and Ag photocatalyst nanoparticles.…”

A simplified in vitro model for investigation of the antimicrobial efficacy of various antiseptic agents to prevent peri-implantitis

“…The oral microbiota is a very complex ecological community that hard to model exactly, since it contains a huge number of culturable and unculturable bacteria which need special demands to their viability and proliferation [15,16]. Our research group previously used Streptococcus strain as a model organism for dental research [17]. Therefore, in this study we also applied a simplified in vitro model and chose pioneer colonizers (Streptococcus mitis, Streptococcus salivarius) to our investigations.…”