Physical Properties of CuO Nanoparticles prepared by Sol - Gel and Hydrothermal methods for Antibacterial Effects

Abstract

Abstract Different sized CuO nanoparticles synthesized by using two methods sol-gel and hydrothermal. In sol–gel method CuO nanoparticles obtained by using Copper nitrate trihydrate [Cu(NO3)2.3H2O],and citric acid were dissolved in de- ionized water. The powder, which was further annealed at different temperature (200,300,400,500, and 600)ºC. In the hydrothermal method CuO nanoparticles obtained by using Copper chloride hydrate [CuCl2.2H2O], and Hexamine (C6H12N4) were dissolved in de-ionized water and stirred by magnetic stirrer to get homogenous solution and transferred into 50 ml Teflon –lined stainless steel vessels (autoclave), and annealed at (200,300, and 400)ºC for 1 hour. The nanoparticles were characterized by XRD, UV-Visible spectroscopy, FTIR, AFM,TEM. The X-ray diffraction spectra of the CuO NPs prepared in the two methods at different temperatures were exhibited the monoclinic structure of CuO which was confirmed from the standard card (JCPDs, No. 05-0661). The lattice constants were found to be a=4.688 ºA, b=3.427 A, c=5.132 A. The crystalline size of CuO NPs prepared in hydrothermal method was found to be (11.2)nm is smaller than the crystalline size of CuO NPs prepared by sol-gel method was found to be (15.3)nm at the same temperature 200ºC. From the results of UV-Visible show a red shift in the absorption spectra due to the increase in the particles size with increase in annealing temperature. The study of the topography of the surface of the particles of CuO NPs by using atomic force microscopy where it was through that measurement study of surface roughness particle size nanoparticles rate plus size distribution of the particles prepared .It is observed that the increased temperature is accompanied by an increase in the size of nanoparticles ,surface roughness increased as increases of the temperatures. In FTIR Spectra were recorded in solid phase using the KBr pellets technique in the range of 4000-400 cm-1. FTIR spectra exhibiting only one vibration mode occurring at approximately 500 cm-1 for all samples assigned for Cu-O stretching vibration, conforming the formation of highly pure CuO nanoparticles . A weak band at round 2340 cm-1 may be attributed to the vibration of atmospheric CO2. The result of the TEM of the CuO NPs prepared by sol-gel& Hydrothermal methods at different temperatures these indicate that the increased temperature was accompanied by an increase in nano size. the size depends on the temperature value where the higher the temperature the larger the nanoparticles size was analyses by Image J. The shape of nanoparticles is spherical. The results of antibacterial activity using CuO NPs which prepared by sol-gel and hydrothermal methods at different temperatures against G(+ve) bacteria and G(-ve) bacteria by well diffusion. In this study, the copper oxide nanoparticles showed remark able antibacterial activity against both Gram-positive bacteria and Gram-negative bacteria. The extent of inhibition of bacteria growth observed it was found to be variable and size dependent. The smallest size NPs synthesized at lowest temperature (200)ºC ,showed a significant inhibitory effect against both Gram(+ve) and Gram(-ve) bacteria as compared to the CuO samples sintered at high temperature. and positive control, a known antibiotic tetracycline against G(+ve) and (-ve) bacteria, that the copper oxide nanoparticles inhibit the growth of both G(+ve) and G(-ve) bacteria and the zone of inhibition decrease with the increase in annealing temperature. the zone of inhibition is maximum when the particles size is minimum these results demonstrate the excellent antibacterial behavior of CuO NPs synthesized at low temperature.