الفهرس 
Inorganic nanoparticles as antimicrobial agentsOnly 14 pages are availabe for public view
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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
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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
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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.