IADR Abstract Archives
Visible Light and UVA Photocatalytic Activity of Silver-Doped TiO2 Coatings
Objectives: Study objectives were to determine if silver-doped TiO2 coatings enhanced photocatalytic activation (PCA) and reduced bacterial attachment compared to controls.
Methods: 12.7 mm diameter titanium grade 4 bar stock was cut into 2 mm disc specimens. Specimens were anodized in a mixed-acid electrolyte containing 3.5 M sulfuric acid, 0.19 M phosphoric acid, 0.25 M oxalic acid, and 0.75 M hydrogen peroxide doped with either 0.05 M silver nitrate or 0.05 M silver acetate to final forming voltages of 144 V. Control specimens were anodized in the same electrolyte without silver additions. X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) were used to determine oxide crystallinity and chemistry. Atomic force microscopy (AFM) and VDI 3198 indentation tests were used to assess surface roughness and oxide layer adhesion. PCA was assessed using a methylene blue (MB) degradation assay under UVA (365 nm, n=6) and visible light (410 nm, n=4) illumination for four hours. S. aureus attachment (n=3) was assessed in specimens after one hour with and without UVA illumination.
Results: XRD showed anatase phase in each oxide, and EDS verified silver in silver-doped oxides. AFM and indentation tests showed similar surface roughness and oxide layer adhesion for all groups. Silver-doped specimens under UVA illumination showed significantly higher PCA compared to controls after 60 (p=0.001) and 240 (p<0.001) minutes. Silver nitrate-doped specimens under visible light showed significantly higher PCA compared to controls after 60 minutes (p=0.045). No significant differences were shown in S. aureus attachment between UVA illuminated and dark specimens from any group.
Conclusions: Silver-doped anatase-phase TiO2 layers showed enhanced PCA under UVA illumination. Silver nitrate-doped specimens also showed promise under visible light. However, no significant differences were shown in S. aureus attachment between silver-doped and control specimens. Future studies are warranted to assess silver-doped oxides against other commonly acquired bacteria.
Methods: 12.7 mm diameter titanium grade 4 bar stock was cut into 2 mm disc specimens. Specimens were anodized in a mixed-acid electrolyte containing 3.5 M sulfuric acid, 0.19 M phosphoric acid, 0.25 M oxalic acid, and 0.75 M hydrogen peroxide doped with either 0.05 M silver nitrate or 0.05 M silver acetate to final forming voltages of 144 V. Control specimens were anodized in the same electrolyte without silver additions. X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) were used to determine oxide crystallinity and chemistry. Atomic force microscopy (AFM) and VDI 3198 indentation tests were used to assess surface roughness and oxide layer adhesion. PCA was assessed using a methylene blue (MB) degradation assay under UVA (365 nm, n=6) and visible light (410 nm, n=4) illumination for four hours. S. aureus attachment (n=3) was assessed in specimens after one hour with and without UVA illumination.
Results: XRD showed anatase phase in each oxide, and EDS verified silver in silver-doped oxides. AFM and indentation tests showed similar surface roughness and oxide layer adhesion for all groups. Silver-doped specimens under UVA illumination showed significantly higher PCA compared to controls after 60 (p=0.001) and 240 (p<0.001) minutes. Silver nitrate-doped specimens under visible light showed significantly higher PCA compared to controls after 60 minutes (p=0.045). No significant differences were shown in S. aureus attachment between UVA illuminated and dark specimens from any group.
Conclusions: Silver-doped anatase-phase TiO2 layers showed enhanced PCA under UVA illumination. Silver nitrate-doped specimens also showed promise under visible light. However, no significant differences were shown in S. aureus attachment between silver-doped and control specimens. Future studies are warranted to assess silver-doped oxides against other commonly acquired bacteria.