Evaluation of the antibacterial activity of Ag-loaded TiO2 nanotubes

Abstract

To date, studies of modified Ti surfaces for biomedical purposes have focused on observations of their morphology and on the identification of the physicochemical properties that influence their biological response. However, for implant materials, antibacterial properties are also of high importance. The use of metal and metal oxide nanoparticles as antimicrobial components of coatings is receiving particular attention. The aim of this work is to create nanoporous oxide layers on Ti with the addition of Ag nanoparticles in order to obtain coatings having both biocompatibility and antibacterial properties for biomedical applications. TiO2 nanotubes (NTs) were grown on a Ti substrate by electrochemical oxidation at constant voltage in a mixture of glycerol, deionized water, and NH4F. Silver particles of size 2-50 nm were deposited on the surface by the sputter deposition technique. The antimicrobial activities of titanium, TiO2-NT, and Ag/TiO 2-NT surfaces were evaluated against four different bacterial strains prevalent in orthopedic infections: S. epidermidis, S. aureus, E. coli, and P. aeruginosa. Our results have shown that Ag nanoparticles can be incorporated into the biomaterial surface in a simple and economic manner suitable for the fabrication of new types of bactericidal materials. The presence of the TiO 2-NT layer significantly reduced the adhesion and biofilm formation of S. epidermidis cells on modified surfaces; the deposition of Ag nanoparticles enhanced the antiadhesive properties of the TiO2-NT layer. Thus, these Ag/TiO2-NT composite layers may be promising for combating post-operative infection for applications in hard tissue replacement procedures. The evaluation of the antimicrobial activity of Ti, TiO2 nanotubes, and Ag-loaded TiO2 nanotubes against four different bacterial strains prevalent in orthopedic infections revealed that the nanotube-based surfaces prevent the adhesion and biofilm formation of S. epidermidis to a significant degree in comparison with Ti. The antiadhesive properties result from the presence of TiO2 rather than Ag. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.