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Abstract The need for novel antibiotics comes from the relatively high incidence of bacterial infection and the growing resistance of bacteria to conventional antibiotics. Consequently, new methods for reducing bacterial activity and the associated infections seem badly needed. Nanotechnology viz., the use of materials with dimensions on the atomic or molecular scale, has become increasingly utilized for medical applications. It has, thus, become great interest as an approach to killing or reducing the activity of numerous microorganisms. While some natural antibacterial materials, e.g., zinc and silver, possess greater antibacterial properties as particle size is reduced into the nanometer regime. The physical structure of a nanoparticle itself and the way in which it interacts with and penetrates into bacteria appears to also provide unique bactericidal mechanisms. This thesis is consists of two parts; in the first part, an attempt was made to prepare different shapes of inorganic metal oxide in nanoscale, namely (CuO, MgO and ZnO ) which were then used as antibacterial agents against Grame positive (Bacillus and S. aureus ) and Grame negative bacteria (E.coli ) . Different methods were used to prepare these oxides, namely (precipitation, sol-gel, ceramic, wet, sonochemical and hydrothermal method). Three shapes of CuO NPs were aimed to be pepared .Two nanorod shapes were formed by using precipitation method at different conditions. One of the nanorod shapes was formed by using precipitation method without using complexing agent. The other one was formed by using 77 ammonia as complexing agent. The third sample of hexagonal shape was prepared by sonochemical method. The hexagonal shape formed by ultrasound irradiation of metal hydroxide. Three shapes of MgO NPs namely, sheet, hexagonal and nanorod shape were prepared by using precipitation and hydrothermal methods. ZnO was found to exist in different shapes (two hexagonal shapes, cone and nanorod shape). Based on XRD results, it could be concluded that all the prepared shapes for all metal oxides under study were pure. The detailed structural characterization of the products was conducted by adopting both the high resolution transmission electron microscopy (HRTEM) and the high resolution field emission scanning electron microscopy (FESEM). The surface parameters of the as prepared nanoparticles with different shapes were estimated by BET measurement such as specific areas and total pore volumes. Antibacterial activities of the prepared metal oxides have been tested on Gram positive (Staphylococcus aureus), (Bacillus) and Gram negative (E. coli) bacteria. The antibacterial activity tests were carried out by the agar diffusion method using the suspension of bacteria spreads on nutrient agar. The inhibitory effect of the prepared metal oxides towards the bacteria (zone of inhibition) was measured and depicted. The size, shape and surface area effect of nanoparticles on the antibacterial efficiency has been investigated. Both CuO and ZnO showed high antibacterial activities. However, the antibacterial performance of MgO was significantly low. The 78 physicochemical characteristics of CuO and ZnO nanoparticles significantly affected their antibacterial performance. On the contrary, the antibacterial activity of MgO was not significantly affected by the criteria of the prepared nanoparticles. It seemed that the ability of MgO to launch the antibacterial process was quite low, so that the impact of their physical properties could not be detected. In the second part of the thesis, the anti-bacterial characteristics of different nano-structured metal and metal oxides modified cotton fabrics were investigated. Silver metal, copper, zinc and magnesium oxides have been supported on bleached cotton fabrics. Reduction, wet method, sol gel and precipitation methods were used in the preparation of the loaded antibacterial nanoparticles (NPs). The preparation of the antibacterialloaded cotton was carried out in-situ and ex-situ by pad dry methods. Formation of the supported nanoparticles was confirmed by using X-ray diffraction (XRD), scanning electron microscopy by (FESEM) and energy dispersive X-ray (EDX) analyses. Antibacterial studies on the supported nanoparticles were performed on Gram positive (Bacillus and S. aureus) and Gram negative (E.coli) bacteria by agar diffusion method. The loaded antibacterial nanoparticles were effecient against the different bacteria under investigation. At the given experimental conditions, the maximum inactivation performance of the loaded inorganic agents were investigated. The loaded fabrics showed the decreasing antibacterial performance order against Bacillus subtilis as follows: Ag = CuO > ZnO > MgO. However, the decreasing activity order against S.aureus and E. coli was CuO > Ag > ZnO = MgO generally The inactivation performances were found to depend on the type, purity and the amount of antibacterial nanoparticles on the textile surfaces. |