Sol-gel derived ZnO/PVP nanocomposite thin film for superoxide radical sensor

Pure ZnO films and ZnO nanoparticle-dispersed polyvinylpyrrolidone (PVP) composite films are prepared on Pyrex glass substrates by the sol-gel dip-coating technique utilizing zinc acetate precursor. The thin films are extensively characterized for surface morphology, chemistry, and nanocrystallite size using various advanced analytical techniques including Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). For the processing conditions considered, ZnO, semiconductor thin films with nanocrystallite size 20-30 nm are obtained. The ZnO nanoparticle size in the PVP composite film increases with increase in ZnO content. The resistance of both the synthesized ZnO and ZnO/PVP thin films decrease significantly after exposure to solution containing superoxide anion radicals (SOR). The results thus indicate that ZnO and ZnO/PVP composite thin films can be used as biosensors for SOR and potentially for characterizing the antioxidant properties of fluids. (c) 2006 Elsevier B.V. All rights reserved.