Preparation and antibacterial activity of titanium nanotubes loaded with Ag nanoparticles in the dark and under the UV light

Highly ordered anatase-type titanium nanotubes (TNTs) arrays were prepared on the surface of titanium by anodization and subsequently heat treatment at 450 °C for 5 h. Three different diameters of TNTs (50 nm, 75 nm, 100 nm) were fabricated via the voltage changed. Then Ag was loaded on these TNTs through a photo-reduction method of AgNO3 solution. Ag particles with the size of approximately 10 nm were uniformly distributed on the surface of TNTs. Samples were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, atomic absorption spectrometry and contact angle test. Meanwhile, the antibacterial activities of Ag-loaded TiO2 nanotubes (TNTs-Ag) were evaluated through antibacterial experiment against both Escherichia coli and Staphylococcus aureus in the dark and under the UV light (λ = 365 nm) irradiation respectively. The results indicated that under the UV light TNTs-Ag had higher antibacterial activities to the two bacteria than TNTs, though the later also showed antibacterial ability. While in the dark environment, the loading of Ag nanoparticles largely enhanced the antibacterial activities of the titanium nanotubes. In addition, the antibacterial efficiencies of all samples increased with increase of nanotube diameters both in the dark and under the UV light. Therefore, TNTs loaded with Ag nanoparticles are expected to be well suited for endo-prosthetic applications due to their excellent antibacterial activities in the dark. And their antibacterial efficiencies can be controlled by adjusting diameters of TNTs, distribution and size of Ag nanoparticles.