Plasma sprayed rutile titania-nanosilver antibacterial coatings

Rutile titania (TiO 2 ) coatings have superior mechanical properties and excellent stability that make them preferential candidates for various applications. In order to prevent infection arising from bacteria, significant efforts have been focused on antibacterial TiO 2 coatings. In the study, titania-nanosilver (TiO 2 /Ag) coatings with five different kinds of weight percentages of silver nanoparticles (AgNPs) were prepared by plasma spray. The feedstock powders, which had a composition of rutile TiO 2 powders containing 1–10,000   ppm AgNPs, were double sintered and deposited on stainless steel substrates with optimized spraying parameters. X-Ray diffraction and scanning electron microscopy were used to analysize the phase composition and surface morphology of TiO 2 /Ag powders and coatings. Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ) were employed to examine the antibacterial activity of the as-prepared coatings by bacterial counting method. The results showed that silver existed homogeneously in the TiO 2 /Ag coatings and no crystalline changed happened in the TiO 2 structure. The reduction ratios on the TiO 2 /Ag coatings with 10   ppm AgNPs were as high as 94.8% and 95.6% for E. coli and S. aureus , respectively, and the TiO 2 /Ag coatings with 100–1000   ppm AgNPs exhibited 100% bactericidal activity against E. coli and S. aureus , which indicated the TiO 2 /Ag coatings with more than 10   ppm AgNPs had strong antibacterial activity. Moreover, the main factors influencing the antibacterial properties of TiO 2 /Ag coatings were discussed with grain size and the content of silver as well as the microstructure of the coatings.