الفهرس 
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Abstract
The present thesis includes four major parts;
Part one:
This part contains the introduction of this thesis. Introduction includes the production/processing of chitosan, the biological and chemical properties of chitosan, modification of chitosan by grafting methods and biological activities of chitosan. In addition to, the synthesis and some applications of poly2-aminothiophenol are present. Finally, this part contains some properties and applications of silver nanoparticles.
Part two:
This part contains the experimental section comprises the chemicals, experimental techniques and tools of analysis. Additionally, the descriptions of the used instruments are given.
Part three:
This part includes the obtained results including the illustrating graphs and tables.
Part four:
This part includes the discussion section represented in our publication.
The main target of this thesis is the synthesis and characterization of p2-aminothiophenol (p2-ATH), chitosan-gr-p2-ATH and assembling it onto silver nanoparticles. The synthesized polymers and their assembled samples on AgNPs were screened for their biological activities as anti-microbial, anti-oxidant, cytotoxicity against human hepatocarcinoma cell lines (HePG2) and arthritic effects.
Oxidative chemical polymerization reaction was investigated for the preparation of p2-ATH and chitosan-gr-p2-ATH. APS was used as an oxidant and the polymerization reaction was completed under N2 atmosphere. This grafting copolymerization reaction was based on 2-ATH attachment on free NH2 group present in chitosan.
After preparation of p2-ATH and chitosan-gr-p2-ATH, assembling on AgNPs was achieved as following: colloidal silver nanoparticles were synthesized by chemical reduction of silver nitrate using tri-sodium citrate; 20 ml of the prepared AgNPs solution is mixed with 5 ml solution of the synthesized polymeric samples in DMF (5 g/l). The mixture was stirred continuously for 24 hrs till colour change The polymer /silver nano composites are rinsed with ethanol and dried in air.
The prepared polymeric structure and their nano-composites were characterized by infrared, ultraviolet-visible spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, and transmission electron microscopy. Through this characterization, the grafting of 2-ATH onto chitosan and assembling of all polymeric samples onto AgNPs were proved.
IR spectroscopy demonstrated that the S-H stretching vibrations appears in the case of p2-ATH at 2610, and 2354 cm-1and in the graft appears at 2613, and 2347cm-1. With assembling, these bands arenot present due to complete thiol group deprotonation and formation of the S-Ag bond.
The UV-visible spectroscopy reveals that the absorption bands appear at 268 &350 nm in the case of p2-ATH and at 270 &348 nm in case of the graft can be attributed to π- π*transitions also present in the in polymeric/AgNPs with small shifts. These bands confirm both the copolymerization and the assembling processes. The UV characteristic band for Ag (0) in the case of colloidal aqueous AgNPs, appears at 438 nm, and in the polymeric/AgNPs composites appears at 351 and 321 nm with blue shift on assembling with p2-ATH and chitosan-gr-p2-ATH respectively.
The XRD patterns show that the synthetized polymeric structures and their composites with AgNPs are crystalline materials. Peaks characterize Ag (0) are existed in the assembled polymeric structures at 2Th ̴38 (111), 44(200), 64 (220), 77 (311).
TEM images of the synthesized Ag nanocomposites showed that AgNPs with almost spherical shape and with an average size ranging from 4.7 to 15.55 nm and 26.3 to 78.9 nm embedded over the matrix of chitosan-gr-p2-ATH/AgNPs and p2-ATH/AgNPs respectively. The average particle size of both chitosan-gr-p2-ATH and p2-ATH is ranging from 11.6 to 40 nm and 10.5 to 81.8 nm respectively. While SEM images showed that chitosan has fibrous structure, p2-ATH and chitosan-gr-p2-ATH have spherical shape. PDI average values depending on both SEM and TEM images are 0.71, 0.83, 0.7, and 0.74 for chitosan-gr-p2-ATH, chitosan-gr-p2-ATH/AgNPs, p2-ATH and p2-ATH/AgNPs respectively. The values of PDI revealed monodispersed polymer samples. In general, the crystallinity was reduced on the assembling process.
The TGA results proved that there is a difference in thermal stability of the prepared structure and their composites, which indicated the grafting and assembling processes.
The prepared polymeric samples and their composites with AgNPs were screened for their biological activities as anti-cancer properties, anti-microbial, anti-oxidant and anti-inflammatory.
The Anti-microbial tests were screened and the obtained data reveal that, the polymeric samples have anti-microbial efficiency higher than that of the assembled samples. Additionally, the grafting of chitosan with p2-ATH enhances the anti-microbial activity of p2-ATH.
Anti-cancer activity against HepG2 were investigated for chitosan and prepared polymeric materials using MTT assay after 24 h of adding various concentrations of polymeric materials (0.977-2000 μg/mL). Data revealed that chitosan-gr-p2-ATH exhibited the strongest cytotoxicity effect on HepG2 with IC50 of 3.07 μg/mL. P2-ATH, p2-ATH/AgNPs and chitosan-gr-p2-ATH/AgNPs showed moderate anti-tumor cytotoxicity effect; they have IC50 8.42, 9.73 and 11.22 μg/mL respectively. While, chitosan illustrated mild effect recording 668.52 μg/mL.
The DPPH scavenging potentials of chitosan and synthetized polymeric structures in the following order of magnitude: gallic acid>chitosan-gr-p2-ATH>p2-ATH>p2-ATH/AgNPs> chitosan-gr-p2-ATH/ AgNPs> chitosan. The tested polymeric structures had a dose-dependent scavenging activity and the scavenging effect increased with the increase of the concentration in the range of 1.25-10 mg/mL.
The anti-inflammatory behavior of the prepared polymeric samples was investigated using CFA arthritic model in mice. The elevated pro-inflammatory and inflammatory mediator (TNF-α) level decreased by the treatment of the arthritic mice with chitosan and/or synthetized polymeric samples, the most potent effect was by p2-ATH/AgNPs followed by chitosan-gr-p2-ATH/AgNPs and p2-ATH. In addition, the level of anti-inflammatory cytokine (IL-4) was variably affected by chitosan and/or synthesized polymeric samples supplementation the highest effect was exhibited by chitosan-gr-p2-ATH/AgNPs then p2-ATH. While, the RF level decreased in the following order of magnitude: p2-ATH>p2-ATH/AgNPs>chitosan-gr-p2-ATH/AgNPs>chitosan>chitosan-gr-p2-ATH.