Antibacterial effects of Ag-HAp thin films on alumina substrates

Ion beam assisted deposition (IBAD) has been successfully used to produce a dense ultra-adherent and pinhole-free hydroxyapatite (HAp) layer on alumina substrates. After deposition the HAp-coated alumina was immersed in 20 ppm and 100 ppm AgNO3 solution to carry out the ion exchange between Ag- and Ca2+ in HAp. An obvious antimicrobial effect against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Staphylococcus epidermidis was observed in the samples treated with 20 ppm AgNO3 solution. In contrast to this, the untreated samples did not show any bactericidal effect. Scanning electron microscopy (SEM) studies showed that Ag-rich phases wen homogeneously distributed on the surface. X-ray diffraction (XRD) demonstrated that the surface structure in the samples without Ag was HAp, whereas with Ag it is HAp and AgCaP. The minimum inhibitory concentration of AgNO3 was measured to be 1.302 mu g/ml. The release of Ag- ions from the Ag-HAp films in simulated body fluid (SBF) solution was determined by atomic absorption spectroscopy. (C) 1998 Elsevier Science S.A. All rights reserved.