الفهرس 
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Abstract
Water contamination by the phenolic compounds is considered a worldwide environmental problem, resulting in the accumulation of toxic substances in the food chain.
Bisphenol A (BPA) is an organic compound that belongs to the phenols group. It is synthesized by the reaction of phenol with acetone in a strong acid medium. The high production rate of BPA is the main reason for its presence in the environment. As BPA was rapidly metabolized, its health effect can be prolonged to the next generations. Several studies confirmed that BPA exposure affects endocrine and reproductive functions, as well as many tissues and systems are sensitive to BPA as the mammary gland, prostate gland, adipose tissue, and brain.
Hydroxyapatite is a form of calcium phosphate chemical that resembles to the mineral composition of bone tissues. HAP had a great interest in medicine and engineering field. HAP was used for many applications as adsorption of harmful metals, fluorescent lamps, fuel cells, and catalysts. It is also characterized by its low cost, low water solubility, high stability, availability, and easy preparation. HAP is used as a sorbent for water treatment, the use of HAP in nanoparticles allows a wide surface area for the adsorption process to take place.
Therefore, the present study was undertaken to find out a suitable and eco-friendly compound to eliminate the harmful effect of BPA by using Hydroxyapatite on nanoscale. The study was performed both in vivo and in vitro. NHAP was prepared using sol-gel technique, and then characterized by a scanning microscope for surface morphology. The size was calculated using the Scherrer equation, FTIR to identify the functional groups and thermal stability was conducted by a Thermal gravemetric instrument.
An adsorption experiment was performed according to several factors such as contact time, concentration, pH, and adsorbent dosage to evaluate the efficiency of prepared NHAP to adsorb BPA. As well as isotherm and kinetic modeling for adsorption was done to describe the type of reaction at which adsorption take place.
In vivo study was conducted on 40 male adult Wistar rats and was divided randomly into 4 groups each of 10 rats. group I (the negative control group) fed on a vehicle solution of 10% DMSO; group II (NHAP group) received nanohydroxyapatite 1g/kg/ b. wt / day; group III(BPA group) ingested with BPA 100mg/kg/b.wt./ day; group IV (NHAP+BPA group) adminstrated 1g NHAP/100mg BPA/kg /b. wt. /day. This study extended to 6 consecutive weeks and doses were administrated via oral gavage.
Blood and tissue samples were collected at the end of the experimental period and then centrifuged to separate sera. Serum levels were used to determine liver functions (ALT, AST, Total protein, and Albumin), and lipid profile (total cholesterol, triglycerides, HDL-C, and LDL-C). Liver tissue homogenates were used to evaluate the oxidative stress, Heme oxygenase-1, and Nrf2. In addition to the histopathological alterations detected in liver tissue sections liver body and liver weight are detected.
The results can be summarized as follows:
The characterization results: The prepared NHAP was in fine, irregular particles and some particles were in clusters, with a size of 65 nm. XRD results showed sharp peaks at 2θ similar to those of the HAP standard. FTIR showed the functional groups of hydroxyl and phosphate and their stretching mode that aligned with standard HAP. The prepared NHAP showed thermal stability.
The adsorption results: the effect of contact time showed fast uptake of BPA at the initial time until reaching a plateau, BPA removal percent increased as the adsorbent dose increased, and the adsorption capacity increased as the pH value decreased.
The isotherm adsorption model results: showed that Freundlich isotherm was fitted to describe the adsorption.
The kinetic adsorption model results: showed that the Pseudo-second-order model was well describing the adsorption.
Body and liver weight results: BPA group showed a significant decrease in body weight gain by 33% and there are no changes in N.C, NHAP, and NHAP+BPA groups. The liver weight of the BPA group showed a significant increase and no changes were observed in the other groups.
Liver function results: Serum ALT and AST activity levels showed a significant increase in the BPA group compared to the negative control and NHAPgroup. On the other hand, the NHAP+BPA group revealed a significant decrease in both levels. Serum levels of total proteins and albumin showed non-significant differences between N.C and NHAP groups but they showed a significant decrease in the BPA group while the NHAP+BPA group was enhanced.
Lipid profile results: The levels of serum cholesterol, triglycerides, and LDL-C were significantly increased in the BPA group while the NHAP+BPA group was near the normal levels, and had no changes in the N.C and NHAP group.
Oxidative stress results: HO-1was significantly decreased in the BPA group while there is no change in N.C and NHAP groups. The treated group showed an improvement in HO-1 values. Nrf2 was greatly decreased in the BPA group with no change in N.C and NHAP group, NHAP+BPA group showed improved results.
Histopathological results: N.C showed normal structure, the NHAP group had no alteration in liver tissues, the BPA group showed histological alteration with hepatocellular necrosis, NHAP+BPA group showed improvement with mild inflammation.
Collectively, the results from the present thesis suggest using NHAP with a dose of 1g/kg/b. wt. as a suitable and promising treatment compound to eliminate the adverse effects of BPA on humans.