Showing papers by "Maher Z. Elsabee published in 2011"

Enhancement and Characterization of Chitosan Extraction from the Wastes of Shrimp Packaging Plants

Abstract: Chitin is the second most abundant carbohydrate polymer in nature next to cellulose. The main source of chitin is crustacean shells. Chitosan, derived from chitin by alkaline deacetylation, characteristically plays an important role in applications. Several parameters determine the chitosan specifications, namely, chitosan sources, incubation time, pretreatment conditions, temperature and acid and alkaline treatment. Chitosan extraction has been achieved by microwave heating and compared with that of conducting the deacetylation in an autoclave. High molecular weight chitosan (as determined by viscosity measurements of chitosan in dilute acetic acid solution), white color, high water binding capacity (WBC) and fat binding capacity (FBC) has been obtained by microwave treatment. In addition, microwave treatment saves a large amount of energy (due to the shorter time of heating) which is a very important factor for commercial productions. The data extracted from X-ray diffraction, nuclear magnetic resonance and Fourier transforms infrared spectroscopy have shown more crystalline and higher DDA of chitosan produced in microwave than the one in autoclave. Moreover, the antibacterial activity of chitosan prepared by microwaves was higher than that produced using the autoclave.

Water-soluble derivatives of chitosan as a target delivery system of 99mTc to some organs in vivo for nuclear imaging and biodistribution

Abstract: Carboxymethyl chitosan, (CMC), and N-lauryl-carboxymethyl chitosan (LCMC), have been prepared as water soluble derivatives of chitosan. These biodegradable chitosan derivatives were characterized and investigated for nuclear imaging and body distribution. They were labeled with 99mTc to use them as targeted delivery to some organs in vivo for nuclear imaging and to follow their biodistribution within the body. The factors controlling the labeling efficiency have been investigated. The percent labeling yield was determined by using ascending paper chromatographic technique. In vivo biodistribution studies of radiolabeled chitosan derivatives were carried out in groups of female Wistar rats, the body distribution profile in rat was recorded by gamma scintigraphy and the biodistribution of 99mTc-labeled compounds in each organ was calculated as a percentage of the injected dose per gram of tissue (%ID/g). It has been found that the biodistribution of the two compounds and the pattern of their liver uptake were markedly different. The present study demonstrates a high potential approach for liver imaging using 99mTc-LCMC. An intriguing finding of this study was that the three samples were excreted rapidly via the kidneys because of the water-soluble nature of chitosan derivatives. This suggests that water-soluble chitosan derivatives are good polymeric carriers for radioactive element that overcomes accumulation in the body. Moreover, the easy and inexpensive availability of chitosan could be beneficial for applications in scintigraphic imaging.

Grafting of acryloyl cyanoacetohydrazide onto chitosan

Abstract: Chitosan was grafted with a novel monomer namely Acryloyl cyanoacetohydrazide (ACAH) which contains carbonyl and cyano groups. The graft copolymerization was conducted in heterogeneous phase using potassium persulfate (K2S2O8) and sodium bisulfite (NaHSO3) as redox initiators. The effect of monomer concentration, initiator concentration and ratio, time and temperature on the extent of grafting (G%) and the efficiency of grafting were studied. Homopolymer formation has not been observed under all the investigated conditions. The grafted samples were characterized by FTIR spectroscopy, X-ray diffraction and thermogravimetric analysis. The crystallinity of the used chitosan was reduced by grafting. Dye uptake of the grafted samples towards the different types of dyes (acidic, and basic) was investigated and was found to improve profoundly over the native chitosan with a higher uptake for the acidic dye. The grafted samples showed an increased swelling in water, which increased further upon quaternization of the graft copolymers. The extent of swelling is higher in acidic and basic media more than in neutral pH. The quaternized graft copolymer was found to be soluble in water. The fungicidal activity of the quaternized graft copolymers towards three soil-borne sugar beets pathogens was investigated in vitro. The effect on the micro organisms is proportional to the amount of ACAH in the graft copolymer.

Synthesis, characterization polymerization and antibacterial properties of novel thiophene substituted acrylamide

Abstract: Ethyl 2-acrylamido-4,5,6,7-tetrahydrobenzo [b] thiophene-3-carboxylate (ETTCA) has been synthesized and its structure has been elucidated by elemental analysis and spectral tools. Free radical polymerization of (ETTCA) has been conducted in several solvents using azobisisobutyronitrile (AIBN) as an initiator. The kinetic parameters of polymerization of the ETTCA were investigated, and it was found that the polymerization reaction follows the conventional free radical scheme. The overall activation energy of polymerization Δ E was determined (Δ E = 45.11 kJ mol −1 ). The copolymerization of ETTCA with three conventional monomers was carried out in dioxane at 65 °C. The monomer reactivity ratios for the copolymerization of ETTCA with methyl methacrylate (MMA), vinyl acetate (VA) and vinyl ether (VE) were calculated. Thermal stability of the ETTCA polymer and its copolymers were investigated by thermogravimetric analysis. It has been found that the prepared polymer (PETTCA) and its copolymers with VA have moderate biological activity and highly dependent on the copolymer composition.

Grafting of N-isopropyl Acrylamide onto Bacterial Polyhydroxybutrate/Hydroxyvalerate Copolymers

Abstract: This work deals with the grafting of N-isopropyl acrylamide (IPA) onto poly (3-hydroxybutyrate-3-hydroxyvalerate), (PHBV) (5.4 mole % 3-hydroxyvalerate), using benzoyl peroxide as free radical initiators. The effect of N-isopropyl acrylamide and initiator concentrations and reaction time on the degree of grafting has been investigated. The maximum degree of grafting was 82%. The grafted products were characterized by FTIR, 1 HNMR, DSC, wide-angle X-ray diffraction and TGA analysis. The DSC results showed that the cold crystallization temperature from the glassy state increased with increasing the extent of grafting, while the Tg and Tm are not affected significantly. TGA analysis revealed that grafting of the host PHBV polymer did not affect much its onset decomposition temperature. The Grafted products swell in aqueous solution and the swelling is controlled by the extent of grafting, temperature, and pH. The biodegradability of PHBV and its graft copolymers solution-cast films was investigated in active...

Lactosaminated N-succinyl-chitosan as a liver-targeted carrier of 99mTc in vivo for nuclear imaging and biodistribution

Abstract: Lactosaminated N-succinyl-chitosan (LNSC), a water-soluble biodegradable derivative of chitosan, was prepared, characterized, and investigated for nuclear imaging and body distribution. The labeling efficiency of LNSC was examined with 99mTc, and the obtained complex was used as liver-targeted delivery system in vivo for nuclear imaging, and its biodistribution within the body was studied. The labeling efficiency with 99mTc was investigated for time of reaction, effect of substrate amount, effect of stannous chloride (SnCl2) concentration, and effect of the pH of the reaction mixture, in order to approach the optimum condition for labeling technique. It was found that the maximum yield for labeling of 2.5-mg 99mTc-LNSC was 96.9% when 50 µg of SnCl2 was used at pH 3.5–5, at room temperature and 5-min reaction time. An in vivo biodistribution study of radiolabeled LNSC was carried out in female Wistar rats, and the body distribution profile was recorded by gamma scintigraphy. The biodistribution of 99mTc-labeled LNSC (99mTc-LNSC) in each organ was calculated as a percentage of the injected dose per gram of tissue (%ID/g). 99mTc-LNSC was shown to be a highly potential approach for liver imaging. Moreover, the rapid excretion of LNSC through the kidneys suggests that water-soluble chitosan derivatives are good carriers of radioactive elements that do not accumulate in the body. The results indicate that the easy and inexpensive extraction, and thus the ready availability, of chitosan and its derivatives makes them potentially useful for applications in scintigraphic imaging.

The Amazing Materials Chitin and Chitosan

Abstract: Chitin is a naturally abundant polysaccharide and the supporting material of crustaceans (such as crabs, shrimps and cuttlefish), insects, and fungi. Chitin is the second most abundant natural polymer after cellulose and estimated to be produced annually almost as much as 10 billion tons. It is a highly insoluble material resembling cellulose in its solubility and low chemical reactivity.Chitosan is the modified N-deacetylated derivative of chitin. Recently, much attention has been paid to chitosan as a potential polysaccharide resource. It has become of great interest since it is inexhaustible, and also as a new functional material of high potential in various fields and recent progress in chitin and chitosan chemistry is quite noteworthy. Chitosan is obtained by deacetylation of chitin using strong alkali solutions. Both polymers are biodegradable, biocompatible and have many biological, biomedical, agriculture and technical applications.The potential applications of chitosan and chitin can be extremely enlarged by conducting chemical modifications using the OH and the NH2 groups. Examples of these modifications are acylation, alkylation, carboxymethylation and grafting.