International Journal of Nanomedicine (Dec 2016)
Biocompatibility and antibacterial activity of nitrogen-doped titanium dioxide nanoparticles for use in dental resin formulations
Abstract
Andrew Zane,1 Ranfang Zuo,2 Frederick A Villamena,3 Antal Rockenbauer,4,5 Ann Marie Digeorge Foushee,1 Kristin Flores,1 Prabir K Dutta,2 Amber Nagy1 1Biomaterials and Environmental Surveillance Department, Naval Medical Research Unit San Antonio, Joint Base San Antonio, Fort Sam Houston, San Antonio, TX, 2Department of Chemistry and Biochemistry, 3Department of Biological Chemistry and Pharmacology, Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University, Columbus, OH, USA; 4Research Centre for Natural Sciences of the Hungarian Academy of Sciences, Institute of Materials and Environmental Chemistry, 5Department of Physics, MTA-BME Condensed Matter Research Group, Budapest University of Technology and Economics, Budapest, Hungary Abstract: The addition of antibacterial functionality to dental resins presents an opportunity to extend their useful lifetime by reducing secondary caries caused by bacterial recolonization. In this study, the potential efficacy of nitrogen-doped titanium dioxide nanoparticles for this purpose was determined. Nitrogen doping was carried out to extend the ultraviolet absorbance into longer wavelength blue light for increased biocompatibility. Titanium dioxide nanoparticles (approximately 20–30 nm) were synthesized with and without nitrogen doping using a sol–gel method. Ultraviolet–Visible spectroscopy indicated a band of trap states, with increasing blue light absorbance as the concentration of the nitrogen dopant increased. Electron paramagnetic resonance measurements indicated the formation of superoxide and hydroxyl radicals upon particle exposure to visible light and oxygen. The particles were significantly toxic to Escherichia coli in a dose-dependent manner after a 1-hour exposure to a blue light source (480 nm). Intracellular reactive oxygen species assay demonstrated that the particles caused a stress response in human gingival epithelial cells when exposed to 1 hour of blue light, though this did not result in detectable release of cytokines. No decrease in cell viability was observed by water-soluble tetrazolium dye assay. The results show that nitrogen-doped titanium dioxide nanoparticles have antibacterial activity when exposed to blue light, and are biocompatible at these concentrations. Keywords: titanium dioxide, antibacterial activity, nitrogen doping
