Low-temperature sol-gel-derived nanosilver-embedded silane coating as biofilm inhibitor

Silver nanocomposite coatings are prepared by the sol-gel method for the prevention of biofilm formation on the surface of medical implanted devices. High-temperature processing of such coatings can lead to diffusion of nanosilver and reduce the amount of available silver particles for long-term effects. Using a low-temperature sol-gel method, we have successfully prepared silane-based matrices, phenyltriethoxysilane (PhTEOS), containing different amounts of Ag nanoparticles. The incorporation of a silver salt into the sol-gel matrix resulted in a desired silver release rate, i.e. high initial release rate followed by a lower sustained release for more than 15 days, as determined by inductively coupled plasma mass spectrometry (ICP-MS). Scanning electron microscopy (SEM) has been employed to investigate the morphology of the film surfaces before and after immersion in a nutrient-rich bacterial suspension of approximately 10⁸ CFU ml⁻¹, which was incubated for up to 30 days at 37 °C. It was found that thin films containing 35 nm particles could prevent the formation of biofilm for over 30 days. The presence of surface silver before and after 3, 9 and 15 days immersion was confirmed by x-ray photoelectron spectroscopy (XPS).