Study of antibacterial composite Cu/SiO₂ thin coatings

In the present work, composite copper containing silicate thin coatings (Cu/SiO₂) were prepared on glass substrates by the sol-gel route. The preparation process included hydrolysis and subsequent polycondensation of corresponding alkoxide under refluxing and addition of soluble salt of antibacterial metal to the resulting sol. The coatings deposited by dipping process, were thermally treated in oxidative and reductive conditions up to 500°C for metal nanoparticles formation. The coating structure and the nanoparticles formation were studied by the X-ray Diffraction (XRD), UV-VIS and Heavy Ion Rutherford Backscattering (HIRBS) Spectroscopies. The antibacterial activity against Escherichia Coli was examined by the so-called antibacterial-drop test. The possible correlation between the layer interdiffusion after the thermal treatment and the antibacterial activity was considered and analyzed. The coatings exhibited a high antibacterial activity, which was enhanced with the increase of the metal concentration and was decreased with the increase of temperature of thermal treatment and metal nanoparticles formation.