Tahia B. Mostafa

Effect of γ-rays on carboxymethyl chitosan for use as antioxidant and preservative coating for peach fruit

Carboxymethyl chitosan (CMCS) was synthesized by alkylation of chitosan using monochloroacetic acid and characterized by FTIR and (1)H-NMR spectroscopies. Different molecular weights (Mws) of CMCS were prepared by radiation degradation of CMCS in the solution form at different irradiation doses. The structural changes and Mw of degraded CMCS were confirmed by UV-Vis, FTIR and GPC. The antioxidant activity of CMCS was evaluated using scavenging effect on DPPH radicals, reducing power and ferrous ion chelating activity assays. The antioxidant activity of CMCS enhanced with decreasing CMCS Mw. The possible practical use of CMCS as preservative coating for peach fruit by dipping treatment after 10 days of storage at ambient temperature was investigated. The CMCS with lower Mw had a good effect on delaying spoilage and decreasing malondialdehyde (MDA) content of peach fruits suggesting their possible use as antioxidant and preservative coating.

Ionic Sal-SG Schiff bases as new synergetic chemotherapeutic candidates: synthesis, metalation with Pd(II) and in vitro pharmacological evaluation

A series of novel N-(salicylidene)-sulfaguanidines (Sal-SG) bearing ionic liquid (IL) terminals (ILSSGH, 4a–f) have been synthesized by Schiff base condensation of IL-functionalized salicylaldehydes (ILSal, 3a–g) and sulfaguanidine (SG). Metalation trials of these ionic Schiff bases with palladium(II) chloride affords the corresponding Pd(II) complexes, [Pd(II)(ILSSG)Cl(H2O)] (5a–g). Further, the antimicrobial profiles of the new compounds against a set of common pathogens have been described. Zone of inhibition (ZOI) and minimal inhibitory concentration (MIC) values revealed that most of the new compounds exhibited significant antibacterial and potential inhibitory activity against Staphylococcus aureus (S. aureus), and this activity is modulated by substituents attached to the ionic liquid core as well as the counter-ion.

Radiation Synthesis and Characterization of Maleic Anhydride/Acrylic Acid Copolymers and Their Heterocyclic Compound Derivatives for Possible Uses as Antibacterial Agents

Preparation and characterization of water‐soluble maleic anhydride/acrylic acid (MAn/AAc) copolymer and its derivatives were studied for possible use as antibacterial agents. Preparation conditions that affect the copolymer yield, molecular weight and polymeric chain distribution were studied. As the irradiation dose increases, the copolymer yield, as well as molecular weight increases. The higher the MAn content in the comonomer feed solution, the lower the copolymer yield. The derivatives of MAn/AAc copolymers of different functional groups were obtained by treating MAn/AAc copolymer with various organic reagents containing reactive amino groups, such as sulpha–drug compounds and amino acid derivatives. Characterization of obtained copolymers using FTIR, 1H NMR, viscometric, and elemental analysis, was carried out. The antibacterial activity of different molecular weight copolymers and their derivatives against gram negative and gram positive bacteria was investigated. The results obtained revealed that such copolymers and the water‐soluble derivatives possessed a broad lethal activity against different types of bacteria and could be used as antibacterial agents.

Effect of Functionalized Multi-walled Carbon Nanotubes with Poly( N -vinyl pyrrolidone- co -2-acrylamido-2-methyl-1-propanesulfonic acid) on the Release of Tramadol Hydrochloride

Multi-walled carbon nanotubes (MWCNTs) were grafted with poly(N-vinyl-2-pyrrolidone) and with poly(2-acrylamido-2-methyl-1-propanesulfonic acid) at different compositions by using γ-rays technique as initiator. The MWCNTs, MWCNT-graft-PNVP, MWCNT-graft-PAMPS and MWCNTs-graft-P(NVP-co-AMPS) were characterized by Fourier transform infra red (FTIR) spectroscopy, X-ray diffraction (XRD), thermal gravimetric analysis (TGA), elemental analysis and high-resolution transmission electron microscopy (HR-TEM). The results indicated that the grafting processes of PNVP, PAMPS and P(NVP-co-AMPS) occurred on to the surfaces of MWCNTs without destroying the framework of MWCNTs. Tramadol hydrochloride (TH) was loaded as model drug and its release behavior was analyzed via various kinetic models. Release of the loaded TH was studied in simulated gastric fluid (SGF, pH = 1.2) and simulated intestinal fluid (SIF, pH = 7.4) at 37 °C. Controlled release of TH from grafted MWCNTs was investigated. The outcome results suggest that the grafted MWCNTs could be used as a promising matrix candidate for oral drug delivery system by harmonization between the composition and pH level of the simulated biological fluids.

Synthesis of Polyvinyl Alcohol/Maleic Acid Hydrogels by Electron Beam Irradiation for Dye Uptake

Novel polyelectrolyte hydrogels based on maleic acid (MA) and polyvinyl alcohol (PVA) were prepared in the presence of electron beams irradiation as initiator and crosslinker. PVA was used as a template for the polymerization of MA in an aqueous solution. The effect of pH on swelling behavior of the hydrogels was examined. In particular, a reversible swelling behavior between acidic and alkaline solutions was investigated. The structure, thermal properties and morphologies of PVA/MA hydrogels were characterized by FTIR, DSC and SEM, respectively. The swelling ratios of gels increased with the increase MA content, pH values, but decreased with enhanced irradiation dose. PVA/MA has been utilized as an adsorbent for the removal of two textile dyes, Reactive red SH.B and Ismative violet 2R, as model dyes from aqueous solution. Factors affecting dye sorption were extensively investigated. The adsorption capacity for dyes increased with the increase of initial dye concentration, contact time, pH, temperature and MA content in the hydrogels. The equilibrium adsorption data were modeled using Langmuir and Freundlich adsorption isotherms. The results revealed that the adsorption of dyes onto PVA/MA hydrogel fit very well with Langmuir isotherm model.

Synthesis, Characterization of Poly (4-vinyl Pyridine/Vinyl Acetate) Organo Montmorillonite Clay Composites Prepared by Chemical Initiation and their Metallated Products

The nanocomposite of different ratios of (4-vinyl pyridine (VP) vinyl acetate (VAc) copolymers), with montmorillonite (Bent), was prepared by direct interaction of sodium montmorillonite (Bent). It was found that the interaction occurred, through ion exchange between sodium cations in Bent and pyridinium ions, in the copolymers. The structure of the prepared composite was confirmed via X-ray diffraction, thermal stability via thermogravimetric analysis and scanning electron microscope. Also, the formation of metallo composites with Cu+2, Hg+2, and Co+2 cations, and their antimicrobial activities were investigated. The results indicated that the prepared composite exhibited antibacterial activities.

Synthesis and characterization studies of γ-radiation crosslinked poly(acrylic acid/2-acrylamido-2-methyl propane sulfonic acid) hydrogels

Abstract Superabsorbent polymer (SAP) hydrogels were synthesized by copolymerization of acrylic acid and 2-acrylamido-2-methyl propane sulfonic acid and their sodium salts. The effects of reaction variables were optimized. SAPs were treated with chemical reagents. The structures and the morphologies of untreated and treated SAP hydrogels were analyzed by different techniques. The swelling/deswelling kinetics of SAP hydrogels, pH and salt sensitivity were investigated. The results show that these samples imbibed about 4310±27 g/g in deionized water, 269±18 g/g in artificial blood and 288±11 g/g in artificial urine. The highest swelling, reversible pH-responsiveness and salt sensitivity of hydrogels widen their applications.

Preparation and characterization of modified chitosan for in vitro controlled release of vitamin B12

Abstract Graft copolymerization of acrylonitrile and acryloyl chloride on to chitosan was prepared by γ-rays. Optimization of the grafting (%) was studied. The grafting (%) was observed to increase with increase in the irradiation dose and monomer concentration. The grafting percentages were about 52% and 36% from polyacrylonitrile and poly(acryloyl chloride), respectively. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to characterize the specimens. The modified chitosan was loaded with vitamin B12, demonstrated nearly 5.0±2.3% and 50.1±4.5% release in the media of pH 1.2 and 6.8, respectively, for amidoximated chitosan-grafted polyacrylonitrile and 3.6±1.1% and 36±2.4% in pH 1.2 and 6.8, respectively, for chitosan-grafted poly(acryloyl chloride), as determined by a traditional dissolution model. The modified chitosan specimens that uploaded with vitamin B12 displayed a more decremental release in the acidic medium than the neutral one. However, in order to incorporate in vivo gastrointestinal conditions, such as acidic pH and high water content in the stomach, low water content, and the presence of semi-solid mass in the large intestine, a new model, called flow through diffusion cell, was also used to study the drug release. The results of the two approaches produced different release profiles at the same pH values.