OBJECTIVE: To explore the preparation methods of nano-silver coating on pure titanium surface and to explore its antibacterial effect on Staphylococcus aureus.

METHODS: (1) Preparation of nano-silver coating on the surface of pure titanium: Hydroxyapatite and silver powder as research objects were fully mixed at a ratio of 20:1. The mixture was ball-milled to ensure the formation of nanosized particles. The mixture of hydroxyapatite and silver powder was put into a stirrer for continuous stirring to ensure the uniform distribution. The mixture was then placed in an ethanol solution followed by insertion of a titanium plate (anode) and a stainless steel plate (cathode). The precipitated powder was obtained on the titanium surface at a voltage of 20 V, and the pure titanium surface with nano-silver coating was prepared after heat treatment in a tube resistance furnace. (2) Observation of antibacterial properties: A minimal inhibitory concentration test was used to determine the antibacterial concentration of the nano-silver coating on the pure titanium surface when shaken with Staphylococcus aureus. A scanning electron microscope was used to observe the structure of Staphylococcus aureus on the pure titanium surface with nano-silver coatings of different mass concentrations.

RESULTS AND CONCLUSION: Nano-silver/hydroxyapatite composite coating and hydroxyapatite coating were relatively uniform. The nano-silver/hydroxyapatite composite coating was white in color but slightly yellowish. The hydroxyapatite coating was white in color. The coating surface was rough and bonded firmly. No peeling of the coating was observed under gross observation. The antibacterial ability of the nano-silver group at 37 ℃ static culture and at 37 ℃ shaking culture was significantly higher than that of the hydroxy-apatite group (P < 0.05). The absorbance value of Staphylococcus aureus at 600 nm in the nano-silver group was lower than that of hydroxyapatite group at 7, 10, 30 hours after intervention (P < 0.05). The layer cells on the nano-silver coating become lighter in color compared with those on the hydroxyapatite coating and there were cells that ruptured and died. The number of Staphylococcus aureus on the nano-silver coating was reduced, and a large number of vacuoles were found. These findings indicate that the 20:1 mixture of hydroxyapatite and silver at micron level can be used to prepare nano-silver coating through ball milling, water bath, ultrasound and heat treatment. The prepared coating can exert excellent antibacterial effects on Staphylococcus aureus.