الفهرس 
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Abstract
Different hydrophilic nanocopmosite hydrogels was prepared by gamma radiation copolymerization to be used in biomedical applications. The results obtained throughout this work may be presented through the following parts:
(I) Gamma Radiation Synthesis and characterization of Hydrogels Based on Starch (PLSt), Acrylic Acid (AAc) and Monmorillonite as nanocomposite (MMT)
A copolymer hydrogels based on different ratios of acrylic acid (AAc) monomers, plasticized starch (PLSt) and Monmorillonite as nanocomposite (MMT) were prepared by gamma radiation copolymerization. The resulted hydrogels were characterized by FT-IR spectroscopy, thermogravimetric analysis (TGA), transmittance electron microscope (TEM), and X-ray diffraction (XRD). The effect of composite and radiation dose on the degree of gelation and swelling of formed hydrogels was also studied to find that increasing the ratio of AAc increases gel fraction while decreases swelling, while MMT increase both gelation and swelling. Sulphanilamide was used as drug model for drug delivery applications. The followings are the important results obtained in this part:
(1) FT-IR spectroscopic analysis showed the characteristic absorption band of all copolymer hydrogel components. While, the different intensity of the peaks suggested copolymerization of AAc onto PLSt/MMT blends, that formed semi inter penetrating polymer network.
(2) Thermogravimetric analysis (TGA) showed that introducing MMT nanoparticles enhanced the thermal stability of the copolymer nanocomposite hydrogels.
(3) Transmission electron microscopy (TEM) cleared the copolymer nanocomposite hydrogels contains well disbursed nanoparticles with a diameter range of 10–40 nm which go along with X ray diffraction (XRD) results that suggested the exfoliation of clay layers into the gel matrix.
(4) The study of drug uptake and release of Sulphanilamide we found that; the uptake and release of the drug depends largely on the MMT ratio in the nanocomposite ; as both of them were found to increase by increasing the MMT ratio. Uptake reaches its maximum within the first hour; while no significant release was observed up to 60 minutes, regardless of composition or MMT ratio, and then we get sudden increase with increasing time.
(5) In the field of biomedical application; the formed films was used as wound dressing; and they had improved the healing rate and quality.
(II) Radiation synthesis of Chitosan (Cs) PLSt co AAc/ MMT copolymer nanocomposite Hydrogels
A composition of (35/65)% PLSt-co-AAc copolymer hydrogel with irradiation dose 15 kGy was chosen to prepare PAAc-co-(PLSt/MMT)/Cs nanocomposite copolymer hydrogels using casting technique; with 10, 20 and 30% Cs; based on starch dry weight, were prepared by gamma radiation copolymerization.
The resulted copolymer hydrogels were characterized by FT-IR spectroscopy, thermogravimetric, analysis (TGA), transmittance electron microscope (TEM), and X-ray diffraction (XRD). Studying the effect of composite and radiation dose on the formed copolymer hydrogels found that while increasing the ratios of both MMT and chitosan-up to 20%- increases gel fraction, increasing Cs decreases swelling property. As drug delivery system, the uptake and release of Sulphanilamide will be studied. The followings are the important results obtained in this part:
(1) FT-IR spectroscopic analysis showed the characteristic absorption band of all copolymer hydrogel components. While, the different intensity of the peaks suggested formation of semi interpenetrating polymer network, that formed semi inter penetrating polymer network, also, shifting of the amino group band of chitosan from 1541.15 to 1621.96 cm 1 supports the presence of interaction between the hydroxyl group and the amino group.
(2) Thermogravimetric analysis (TGA) illustrated the multiple stage thermal decomposition of the copolymer hydrogels. The thermal stability was enhanced with introducing both MMT and Cs to the matrix and the hydrogel based on PAAc-co-(PLSt/MMT)/Cs copolymer hydrogel with 30% Cs displayed the highest thermal stability at the different heating temperatures.
(3) X-ray diffraction (XRD) cleared the dispersion and the exfoliation of MMT clay within the matrix hydrogels, which go along with transmission electron microscopy (TEM) results that clared the diameter of nannocomposite ranges from 10 to 40 nm.
(4) The study of uptake and release of Sulphanilamide drug from the copolymer hydrogels found that the uptake of drug increased by increasing both MMT and Cs content in the initial feed solution; reaching the maximum within the first hour, also the release of Sulphanilamide drug was found to increase with increasing the ratios of Cs.
(5) As an important field of biomedical application applying PAAc-co-(PLSt/MMT)/Cs copolymer nanocomposite hydrogels films as wound dressing, had improved the healing rate and quality, as introducing the Cs to the matrix has dramatically decreased the time required to reach complete healing .
(III) Gamma Radiation Synthesis, characterization and Drug Delivery Application of Poly(Vinyl Pyrolidone) (PVP) /Sodium Alginate (SA )/Ag NPs nanocomposite Hydrogels
Hydrogel beads of SA / PVP with total concentration of 5% w/v. Different concentrations of silver nitrate been mixed with former solution to prepare SA / PVP /Ag nonocopmosite. The beads were allowed to harden in 100ml 1M calcium chloride solution overnight, then filtered, washed with distilled water and irradiated under water at different radiation doses. The followings are the important results obtained in this part:
(1) Transmission electron microscopy (TEM) showed good dispersion for nanoparticles with a diameter range of 10–50 nm.
(2) The gel fraction of hydrogels decreases with increasing both of alginate and AgNO3 ratios, also increasing irradiation dose above 20 kGy decreases the gel fraction.
(3) The degree of swelling of the prepared hydrogels, in distilled water at room temperature and pH 7, increased gradually up to four hours and then increases greatly up to the equilibrium state; and also increased with decreasing gamma irradiation dose and PVP ratios.
(4) FT-IR spectroscopic analysis showed the characteristic absorption band of all copolymer hydrogel components. However, the intensity difference suggests copolymerization of SA / PVP blends, that formed semi inter penetrating polymer network.
(5) Thermogravimetric analysis (TGA) nanocomposite hydrogels displayed higher thermal and that the char yield of hydrogels containing Ag nanoparticle was 42 % when heated up to 600 °C, whereas for the hydrogel without Ag nanoparticles was only 7%.
(6) Using Prednisolone as drug model, uptake-release characters of the formed nanocomposites, had been studied, the release increased with increasing time of release to reach maximum value after 60 min and then tends to reach equilibrium state after 180 min, regardless of the effects of Ag NPs contents, PVP/SA composition and irradiation dose, at different pHs, the best release was at pH, making our hydrogel good for drug duodenum drugs.