الفهرس 
Review of LiteratureOnly 14 pages are availabe for public view
 |  | from | 280 |  |  |
| | | from | 280 | | |
Abstract
For drinking water to be wholesome it should not present a risk of infection or contain unacceptable concentrations of hazardous chemicals to health as toxic metal ions and should be aesthetically acceptable to the consumer.
The objective of this study was to synthesize mesoporous silica silver nanoparticles having strong antibacterial activity and high adsorption capacity to be applied in water purification as an effective alternative for traditional methods that are used in water purification.
To achieve this target this study was designed to determine a method for the synthesis of small sized mesoporous silica silver nanoparticles, characterization of the synthesized nanoparticles, evaluation of the antibacterial activity of the obtained nanoparticles against Gram negative E. coli ATCC 5087, P.aeruginosa ATCC 9027 and S.typhi ATCC 700931 and Gram positive Methicillin-Resistant S.aureus ATCC 43300 (MRSA) as an important pathogens contaminating drinking water, assessment of the antibacterial activity of the synthesized nanoparticles at different temperatures and different pH values, evaluation of the antibacterial activity of the synthesized nanoparticles against a mixed culture of the tested bacteria (E. coli, P.aeruginosa, S.typhi and S.aureus), evaluation of the in vitro cytotoxicity of the synthesized nanoparticles, determination of the action of the synthesized nanoparticles on the ultrastructure of the tested bacterial strains, detection of protein profile of the treated tested bacteria with the synthesized nanoparticles and application of the synthesized nanoparticles in metal removal from both synthetic and natural water samples (surface and ground water), controlling of the growth of both Total Coliform and Fecal Coliform in natural water samples and prevention of biofilm formation of the tested bacteria (E. coli, P.aeruginosa, S.typhi and S.aureus).
The obtained results revealed that:
Mesoporous silica silver nanoparticles Ag/NH2-KIT-6 (x) with weight ratio of silver metal 1.1, 2.4, 3.2 and 7.1 % was synthesized successfully by chemical reduction method. The snenthesized materials were characterized using X-ray diffraction (XRD), FTIR spectra, X-ray photoelectron spectroscopy (XPS), UV-Visble spectroscopy, inductive coupled Plasma (ICP) and transmission electron microscopy (TEM), which revealed the formation of mesoporous silica silver nanoparticles.
The average particle’s size of the synthesized Ag/NH2-KIT-6 (x) with weight ratio of silver metal 1.1, 2.4, 3.2 and 7.1% were found to be 8, 6.5, 10 and 5nm respectively.
In comparison with standard antibiotics, maximum inhibition zone diameters was detected when the silver concentration 7.1% was used against E. coli, P.aeruginosa, S.typhi and S.aureus with diameters of 33, 32, 27 and 30 mm respectively reveling the higher antibacterial activity of Ag/NH2-KIT-6 (7.1%) than the standard antibiotics used.
The antibacterial activity of mesoporous Ag/NH2-KIT-6 (x) was also evaluated using the MIC and MBC tests and the lowest MIC and MBC were obtained when Ag/NH2-KIT-6 (7.1%) was used against E. coli, P.aeruginosa, S.typhi and S.aureus with the concentrations 0.041 & 0.041, 0.013 & 0.041, 0.013 & 0.041 and 0.041& 0.12 mg/ml respectively.
Mesoporous Ag/NH2-KIT-6 (7.1%) exhibited notable antibacterial activity against the tested bacteria (E. coli, P.aeruginosa, S.typhi and S.aureus) at a wide range of temperatures (20, 25, 30, 37, 40 and 43°C) and pH values (6, 7, 7.5 and 8) with maximum activity was detected at 37°C and pH 6.
Mesoporous Ag/NH2-KIT-6 (x) with the low concentration 0.002mg/ml exhibited better antibacterial activity against a mixed culture of the tested bacteria than its antibacterial activity against each individual tested bacterium which required higher concentrations of the synthesized nanoparticles and this result could be obtained due to the influence of the provided optimum conditions (37°C and pH 6) and the microbial antagonism of the tested bacteria.
Antibacterial activity of Ag/NH2-KIT-6 (x) was found to be dose and time dependent and 2 hours of interaction with mesoporous Ag/NH2-KIT-6 (7.1%) was found to be sufficient to kill a mixed culture of the tested bacteria.
In vitro cytotoxicity tests of mesoporous silica silver nanoparticles with weight ratio of silver metal 1.1, 2.4, 3.2 and 7.1% against two human cancer cell lines (Hepatocellular carcinoma and colon carcinoma cells) in addition to normal human lung fibroblast displayed cytotoxic impacts against both Hepatocellular carcinoma and colon carcinoma cells with more cytotoxic effect against Hepatocellular carcinoma than Colon carcinoma on the contrary, mesoporous Ag/NH2-KIT-6 (x) with the weight ratio of silver metal 1.1, 2.4, 3.2 and 7.1% displayed antibacterial activity against the tested bacteria without being harmful to normal human lung fibroblast at 0.12, 0.12, 0.37 and 0.37 mg/ml respectively that are representing the highest MBC values was found to be lethal for each tested individual bacteria and 0.002 mg/ml for a mixed culture of the tested bacteria.
The electron micrographs of both untreated and treated bacterial cells with Ag/NH2-KIT-6 (7.1%) were examined by TEM revealed major damage in their cell membranes.
Protein electrophoresis of both treated S. aureus and E.coli with mesoporous Ag/NH2-KIT-6 (7.1%) showed changes in their protein profile in comparison with their untreated cells as seven de novo bands with molecular weights 190.92, 174.851, 148.012, 118.889, 76.47, 16.805 and 13.836 KDa were induced in treated S. aureus and four de novo bands were induced in treated E.coli with molecular weights 122.23, 46.52, 33.44 and13.83 KDa.
Higher adsorption capacity of Cr (IV) was obtained with mesoporous Ag/NH2-KIT-6 (3.2%) than mesoporous Ag/NH2-KIT-6 (7.1%) when they were applied in Cr (VI) removal from synthetic water due to the low surface area for the later than the former. Silver metal not only displayed adsorption capacity of Cr (IV) but also play a role in the reduction of highly toxic Cr (VI) to non toxic Cr (III).
Equal adsorption rate of Cu (II) was found when either mesoporous Ag/NH2-KIT-6 (1.1%) or mesoporous Ag/NH2- KIT-6 (2.4%) was applied in Cu (II) removal from synthetic water. Mesoporous Ag/NH2-KIT-6 (7.1%) showed good adsorption capacity for metal ions like Al3+, Ba2+, Cr6+, Fe3+, Pb2+, Ni2+, Co3+, Zn2+, Cu2+ and Mn7+when applied in the collected water samples (surface and ground water).
Mesoporous Ag/NH2-KIT-6 (7.1%) showed high percentage of growth reduction of total coliform and fecal coliform representing was 99.99 & 100% and 99.99 &100% respectively in case of surface and ground water samples respectively.
Mesoporous Ag/NH2-KIT-6 (7.1%) showed excellent antibacterial activity and inhibited biofilm formation by all of the tested bacteria (E.coli, P.aeruginosa, S. typhi and S. aureus).