Capping antibacterial Ag nanorods aligned on Ti interlayer by mesoporous TiO2 layer

In this work, aligned and compact Ag nanorods capped by sol–gel mesoporous TiO2 layer were grown on Ti/Si(100) in order to be applied in antibacterial applications. The Ag nanorods with a high effective surface were grown by applying an electric field perpendicular to the surface of the Ag/Ti/Si thin film while it was being heat-treated at 700 °C in an Ar + H2 ambient. The grown silver nanorods had widths and lengths of 20–50 and 250–500 nm with an abundance in {100} facet, respectively. The TiO2 cap layer also had the specific surface area, the total pore volume and the pore diameter of 474 m2/g, 0.49 cm3/g and 8.0 nm, respectively. Antibacterial activities of the TiO2-capped Ag nanorods against E. coli bacteria were examined in the dark and under UV irradiation, and then compared to the corresponding activities of the TiO2-capped Ag thin film and the TiO2-capped Ag nanoparticles grown on the Ti layer. The Ag+ ion release measurements showed that the mesoporous and aqueous TiO2 cap layer can control the silver release process by inter-diffusion of water and silvers thorough its capillary structures, completely different from the ion release behavior of the silver nanorods not capped by the TiO2 layer. The results showed a strong and lasting antibacterial activity for the TiO2-capped Ag nanorods with 2.34 h− 1 for the relative rate of reduction of the number of viable bacteria.