Preparation of PVP-coated copper oxide nanosheets as antibacterial and antifungal agents
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Fatemeh Shayesteh School of Environmental Science and Natural Resources, Faculty of science and technology, University Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia
Nilofar Asim Solar Energy Research Institute, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia
Nabi Motallebi ACECR (Academic Center for Education, Culture and Research), 14155-4364 Tehran, Iran (Received 18 May 2013; accepted 4 October 2013)
Copper oxide (CuO) nanosheets synthesized in polyvinylpyrrolidone (PVP) were characterized with respect to antimicrobial activity by quick precipitation method. Different sizes and shapes of CuO nanosheets were obtained by simple variations of PVP concentrations. The x-ray diffraction results revealed the formation of pure-phase CuO with monoclinic structure. Transmission electron microscopy analysis showed that the average ratio of length to width of these nanosheets increased with increasing PVP concentrations. Due to the quantum size effect, CuO nanosheets exhibit a blue shift in the ultraviolet-visible spectra. Field emission scanning electron microscopy results showed that as the concentration of PVP increased, well-defined morphologies were formed on the surface of the products. Energy dispersive analysis of x-ray clearly confirmed the presence of Cu and O with an atomic ratio of 1:1. Fourier transform infrared spectroscopy results showed that C5O in PVP coordinated with CuO and formed a protective layer. The mechanism of the reaction was also discussed. CuO nanosheets in suspension showed activity against a range of bacterial pathogens and fungi with minimum bactericidal concentrations (MBCs) ranging from 100 to 5000 lg/mL. The extent of the inhibition zones and the MBCs was found to be size-dependent.
I. INTRODUCTION
Among all the functional materials synthesized at the nanometer scale, metal oxides are the main attractive candidates from a scientific and technological point of view. Metal oxide nanoparticles have a unique structure, high surface area, interesting and unusual redox and catalytic properties, good mechanical stability, and good biocompatibility. As a result, these materials have become important components in the field of biomedical therapeutics, bioimaging, and biosensing.1 The bactericidal effectiveness of metal oxide nanoparticles has been proposed to be due to their distinct properties. Such characteristics should allow them to interact closely with bacterial membranes rather than the effect being solely due to the release of metal ions. The mechanism by which nanomaterials may alter biological systems is dependent on their size, shape, composition, and surface properties.2 Copper oxide (CuO) is a transition metal oxide with a p-type semiconducting a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2013.316 J. Mater. Res., Vol. 28, No. 22, Nov 28, 2013
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material and has monoclinic crystal structure with many practical applications, such as antimicrobial,3,4 photother
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