Silver on PEG-PU-TiO2 polymer nanocomposite films:: An excellent system for antibacterial applications

Silver impregnated on polymer-titania nanocomposite films exhibit excellent antibacterial properties with the added advantage of repeated use. The polyethylene glycol-polyurethane-titania designated as PEG-PU-TiO2 polymer nanocomposite films were synthesized by simple solution casting technique. Silver has been incorporated into these films by photochemical reduction of silver nitrate solution. The TiO2 facilitated the UV photoreduction of AgNO3 to Ag, which is active as an antibacterial agent. Fourier Transformed Infrared Spectroscopy (FT-IR) confirms the formation of the polymer, polyurethane. X-ray Diffraction (XRD) determined the structure and scanning electron microscopy (SEM), the morphology of the films. XPS confirms the Ag to be in zero oxidation state and the amount of silver impregnated in the films as estimated by scanning electron microscopy -energy-dispersive X-ray analysis (SEM-EDAX), and atomic absorption spectroscopy (AAS) is about 2-4 at %. The antibacterial properties of these films were studied on Escherichia coli and Bacillus subtilis by the disk-diffusion method and this has been correlated with the percentage of Ag in the films. One very encouraging observation is that the antibacterial activity of the Ag in polymer-titania nanocomposite films showed reasonable activity even when tested in the microbial broth.