Long-Term Antibacterial Performance and Bioactivity of Plasma-Engineered Ag-NPs/TiO2

We prepared TiO2 nanotubes (NT) on commercially pure titanium (cp-Ti) substrate by plasma electrolyte oxidation and adapted magnetron sputtering for incorporation of Ag-nanoparticles (Ag-NPs) onto the nanotubes (Ag-NPs/TiO2 nanotube). Power input to the Ag target per unit time was varied (5, 10, 15 W/cm2) to fabricate different shapes of Agnanoparticles onto the nanotubes while net energy input was fixed by maintaining a constant total sputter time (30, 15, 10 s, respectively). For investigation of experimental samples' characteristics, FE-SEM, TEM, EDS, XRD, XPS, SPM analysis and contact angles measurement was carried out. Through these characterization, plasma engineered Ag-NPs was successfully formed on/in the entire nanotube structure. In terms of antibacterial ability, plasma engineered Ag-NPs/TiO2 nanotubes samples significantly reduced S. aureus colony numbers compared with control. Also, simulated body fluid immersion tests with hydroxyapatite showed ion precipitation onto the surface of all experimental groups, confirmed by XRD and EDS analysis. However, plasma engineered Ag-NPs/TiO2 nanotubes groups were not cytotoxic. Furthermore, MC3T3-E1 cells were cultured on Ag-NPs/TiO2 nanotubes groups to evaluate the effect of nanostructured surface on cell functionality such as a cell proliferation and ALP activity. Ag-NPs/TiO2 nanotubes have both biocompatible and antibacterial characteristics.

Tailoring of antibacterial Ag nanostructures on TiO2 nanotube layers by magnetron sputtering.

To reduce the incidence of postsurgical bacterial infection that may cause implantation failure at the implant-bone interface, surface treatment of titanium implants with antibiotic materials such as silver (Ag) has been proposed. The purpose of this work was to create TiO2 nanotubes using plasma electrolytic oxidation (PEO), followed by formation of an antibacterial Ag nanostructure coating on the TiO2 nanotube layer using a magnetron sputtering system. PEO was performed on commercially pure Ti sheets. The Ag nanostructure was added onto the resulting TiO2 nanotube using magnetron sputtering at varying deposition rates. Field emission scanning electron microscopy and transmission electron microscopy were used to characterize the surface, and Ag content on the TiO2 nanotube layer was analyzed by X-ray diffraction and X-ray photoelectron spectroscopy. Scanning probe microscopy for surface roughness and contact angle measurement were used to indirectly confirm enhanced TiO2 nanotube hydrophilicity. Antibacterial activity of Ag ions in solution was determined by inductively coupled plasma mass spectrometry and antibacterial testing against Staphylococcus aureus (S. aureus). In vitro, TiO2 nanotubes coated with sputtered Ag resulted in significantly reduced S. aureus. Cell viability assays showed no toxicity for the lowest sputtering time group in the osteoblastic cell line MC3T3-E1. These results suggest that a multinanostructured layer with a biocompatible TiO2 nanotube and antimicrobial Ag coating is a promising biomaterial that can be tailored with magnetron sputtering for optimal performance.

Fabrication of bioactive, antibacterial TiO2 nanotube surfaces, coated with magnetron sputtered Ag nanostructures for dental applications.

We investigated whether a silver coating on an anodic oxidized titania (TiO2) nanotube surface would be useful for preventing infections in dental implants. We used a magnetron sputtering process to deposit Ag nanoparticles onto a TiO2 surface. We studied different sputtering input power densities and maintained other parameters constant. We used scanning electron microscopy, X-ray diffraction, and contact angle measurements to characterize the coated surfaces. Staphylococcus aureus was used to evaluate antibacterial activity. The X-ray diffraction analysis showed peaks that corresponded to metallic Ag, Ti, O, and biocompatible anatase phase TiO2 on the examined surfaces. The contact angles of the Ag nanoparticle-loaded surfaces were significantly lower at 2.5 W/cm2 input power under pulsed direct current mode compared to commercial, untreated Ti surfaces. In vitro antibacterial analysis indicated that a significantly reduced number of S. aureus were detected on an Ag nanoparticle-loaded TiO2 nanotube surface compared to control untreated surfaces. No cytotoxicity was noted, except in the group treated with 5 W/cm2 input power density, which was the highest input of power density we tested for the magnetron sputtering process. Overall, we concluded that it was feasible to create antibacterial Ag nanoparticle-loaded titanium nanotube surfaces with magnetron sputtering.