Prevention of hospital infections using Ag/ZnO nanoparticle visible light photocatalyst
Authors: Saoud Khaled 
Published: November 2013

hospital infection due surface contamination becomes very important field of study in recent years. Such contamination can provide a good environment for different microorganisms (i.e. bacteria, viruses, and fungi) to grow and transmit infectious diseases when they come into contact with human body . Recent studies show that surface contamination is accounted for 100,000 deaths in United States alone. Antibacterial coatings has been utilized in many fields such as healthcare, industrial and homes to prevent microorganism's growth and used in sterilization processes. Typically, Semiconductors photocatalysts are used as antibacterial coatings to prevent hospital infections, these materials has ability to interact with light through oxidative process to release radicals to destroy bacteria and viruses. Conventional Metal oxides Semiconductor such as TiO2, ZnO have drawn much attention during the last few years because of their novel photocatalytic activity, availability, stability, strong oxidative capacity, and low cost , . However, due to their wide band gap and high excitation binding energy they only allow absorption in the UV region of solar spectrum. Nanomaterials offered cost-effective solutions for many environmental problems such as waste water treatment, pollution, and anti-bacterial treatment . . It has been known that pure ZnO exhibits low photocatalytic activity due to rapid recombination of photo-activated electrons and holes. It is expected that doping ZnO with metals will improve the photocatalytic activity and disinfection effect. Here report two step synthesis method of Ag/ZnO Nanoparticle heterogeneous Photocatalyst for anti-microbial treatment in hospitals. Our results indicate that Ag/ZnO exhibits high photocatalytic activity and disinfection effect by extending the absorption to the visible range of solar spectrum and prevent the recombination. The nanostructures of the prepared Ag/ZnO particles have been confirmed using UV-VIS absorbance, XRD, and SEM analysis. Antibacterial properties of the Ag/ZnO nanoparticles were investigated by inhibition testing against E. coli using filter sheet. The results, revealed an obvious zone of inhibition around the Ag/ZnO nanoparticles sheet, suggesting the antibacterial property of the Ag/ZnO nanoparticles. The Ag/ZnO system is tested in the presence of visible light and in the dark. The results indicate that Ag/ZnO nanoparticles exhibit antibacterial activity even in the dark. We attributed the photocatalytic activity of the Ag/ZnO Photocatalyst to the Plasmon surface effect of Ag nanoparticles and interaction of Ag with ZnO where Ag nanoparticles act as an electron sink, promoting interfacial charge transfer and reducing charge recombination. Dastjerdi, R., Montazer, M. 2010. A review on the application of inorganic nano-structured materials in the modification of textiles: Focus on anti-microbial properties. Colloids and Surfaces B: Biointerfaces 79: 5-18. Onaizi, S.A., Leong, S.S.J. 2011. Tethering Antimicrobial Peptides. Biotech. Advances 29:67-74. Hoffmann, M. R.; Martin, S. T.; Choi, W.; Bahnemann, D. W. Chem. Rev. 1995, 95,69