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Search Results: 1 - 10 of 1112 matches for " Chitosan "
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Preparation of biocompatible magnetic microspheres with chitosan  [PDF]
Mohamed K. Nasra, Moustafa M. Mohamed, Mohamed A. Elblbesy, Bothaina A. Hefney
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2011, DOI: 10.4236/jbnb.2011.22024
Abstract: Microsphere is a term used for small spherical particles, with diameters in the micrometer range (typically 1μm to 1000μm (1mm)). Microspheres are sometimes referred to as microparticles. Microspheres can be manufactured from various natural and synthetic materials. The present work we prepared chitosan magnetic microspheres (CMMS) with simple crosslinking method. The obtained CMMS were in size range of 1000-2600 nm with average particle size of 1800nm. All the essential characterizations of prepared CMMS were done and the results were in a good agreement with other magnetic microspheres prepared with different method. To test the biocompatibility of CMMS with blood, the effect of them on erythrocytes aggregation and blood hemolysis were studied. Our results showed that CMMS work as good compatible materials with blood.
Comparative Study of Adsorption of Copper Ion onto Locally Developed and Commercial Chitosan  [PDF]
Sunday Anthony Akolo, Abulsalami Sanni Kovo
Journal of Encapsulation and Adsorption Sciences (JEAS) , 2015, DOI: 10.4236/jeas.2015.51003
Abstract: Chitosan synthesized locally with a degree of deacetylation 71% and chitosan with a degree of deacetylation 68% from Sigma Aldrich were used to investigate adsorption of Cu2+ ion in aqueous solution. The results obtained from equilibrium isotherm adsorption studies of Cu2+ ion were an-alyzed in five adsorption models namely: Langmuir, Freundlich, Temkin, Elovich and Dubin- Ra-dushkevich. The isotherms equation was indicated to be well fitted to Langmuir, Freundlich, Temkin and Elovich under the concentration range studied. The kinetic parameters were evaluated utilizing the pseudo-first-order and pseudo-second-order equations, and the adsorption kinetics followed the mechanism of the pseudo-second-order equation for all systems studied, evidencing chemical sorption as the rate-limiting step of adsorption mechanism and not involving a mass transfer in solution. The FTIR studies revealed that the greater sorption of heavy metal was attributed to the large number of primary amine groups available on the surfaces of the chitosan and the abundant carboxyl groups on chitosan.
Properties and Structure of Microcrystalline Chitosan and Hydroxyapatite Composites  [PDF]
Luciano Pighinelli, Magdalena Kucharska
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2014, DOI: 10.4236/jbnb.2014.52015
Abstract:

The skeletal system in the human body is very important, provides support and gives shape to the body and provides a network between all soft tissues. The most common problems in hard tissues are bone fractures, defects or diseases which needed to be treated. The developments in artificial bone area seem to solve most of the hard tissue problems, on the other hand artificial bones themselves may cause other problems and in many cases they do not have sufficient mechanical properties and/or good biocompatibility. The importance of chitosan and its derivatives like microcrystalline chitosan has grown significantly over the last two decades due to its renewable and biodegradable source, and also because of the increase in the knowledge of its functionality in the technological and biomedical applications. The excellent biocompability, biofunctionality, and non-antigenic property make the chitosan and its derivatives as a microcrystalline chitosan an ideal material for tissue regeneration. To improve the suitability of chitosan for bone tissue engineering, the composites of MCCh and hydroxyapatite were studied. In the present work the characterization of the MCCh and composites with HAp in form of films and sponges, is based on physico-chemical tests, morphology, structure, particle size of HAp powder and distribution in the polymer matrix. The compositions with film and sponge shape are derived from the junction of two different materials, containing organic and inorganic substances. All sponge preparations, with HAp/MCCh have a well-shaped 3-dimensional structure, which could be used as implants in orthopedic surgery for a scaffolds base for medical applications.

A Simple Colorimetric Method for the Evaluation of Chitosan  [PDF]
Mohamed Abou-Shoer
American Journal of Analytical Chemistry (AJAC) , 2010, DOI: 10.4236/ajac.2010.12012
Abstract: A simple sensitive and rapid colorimetric method has been developed, and herein described, for the qualitative and quantitative chemical assessment of the commercially available chitosan products. The described method relies on the reactivity of the basic amino function of chitosan with the acid dye bromocresol purple. The applied technique allows assessment of variability and selectivity changes in the quality of the marketed chitosan products.
Preparation and Characterization of Homogeneous Hydroxyapatite/Chitosan Composite Scaffolds via In-Situ Hydration  [PDF]
Hong Li, Chang-Ren Zhou, Min-Ying Zhu, Jin-Huan Tian, Jian-Hua Rong
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2010, DOI: 10.4236/jbnb.2010.11006
Abstract: Hydroxyapatite(HAP)/Chitosan(CS) composite is a biocompatible and bioactive material for tissue engineering. A novel homogeneous HAP/CS composite scaffold was developed via lyophilization and in situ hydration. A model CS solution with a Ca/P atom ratio of 1.67 was prepared through titration and stirring so as to attain a homogeneous dispersion of HAP particles. After lyophilization and in situ hydration, rod-shaped HAP particles (5 μm in diameter) within the CS matrix homogeneously scattered at the pore wall of the CS scaffold. X-ray diffraction (XRD) and Fouri-er-Transformed Infrared spectroscopy (FTIR) confirmed the formation of HAP crystals. The compressive strength in the composite scaffold indicated a significant increment over a CS-only scaffold. Bioactivity in vitro was completed by immersing the scaffold in simulated body fluid (SBF), and the result suggested that there was an increase in apatite formation on the HAP/CS scaffolds. Biological in vivo cell culture with MC 3T3-E1 cells for up to 7 days demonstrated that a homogeneous incorporation of HAP particles into CS scaffold led to higher cell viability compared to that of the pure CS scaffold or the HAP/CS scaffold blended. The results suggest that the homogeneous composite scaffold with better strength, bioactivity and biocompatibility can be prepared via in vitro hydration, which may serve as a good scaffold for bone tissue engineering.
Grafting Vinyl Monomers onto Chitosan:IV:Graft Copolymerized of Acrylicacid onto Chitosan Using Ceric Ammonium Nitrate as the Initiator— Characterization and Antimicrobial Activities  [PDF]
Manoj Kumar Pati, Padmalochan Nayak
Materials Sciences and Applications (MSA) , 2011, DOI: 10.4236/msa.2011.212232
Abstract: Acrylicacid was grafted onto chitosan by using the ceric ammonium nitrate as the initiator. The effect of initiator concentration, monomer concentration, time & temperature on % G and % GE were studied. The grafted samples were characterized using FTIR, TGA, SEM and XRD methods. From the FTIR data it was ascertained that grafting has occurred considerably. The morphology of the grafted polymer was observed from the SEM picture. The thermal analysis indicated the different stages of degradation of the grafted copolymer. Evidence of grafting was obtained from comparison of SEM, XRD, and FTIR of the grafted and nongrafted chitosan as well as solubility characteristics of the products. The antibacterial and antifungal activities of the grafted polymer have also been investigated.
Alginate Reinforced Chitosan and Starch Beads in Slow Release Formulation of Imazaquin Herbicide—Preparation and Characterization  [PDF]
Lami A. Nnamonu, Rufus Sha’Ato, Ikenna Onyido
Materials Sciences and Applications (MSA) , 2012, DOI: 10.4236/msa.2012.38081
Abstract: In a bid to make slow release formulations of imazaquin, the herbicide was encapsulated in starch and chitosan beads reinforced with alginate. The beads were characterized using SEM, DSC and FTIR. Two types of formulations were made by extrusion into 0.25 M calcium chloride solution: chitosan/alginate (LNCI) and starch/alginate (LNSI) beads, and the third was by gelatinization of starch at 75?C (LNSI2). Findings showed highly porous spherical beads, the starch/alginate beads bigger and less porous than the chitosan/alginate beads with diameters of 2.53 ± 0.01 and 2.31 ± 0.01 mm; porosity of 57.58% ± 0.2% and 81.28% ± 0.2% and swelling of 34.91% ± 0.2% and 80.35% ± 0.2%, respectively. FTIR revealed a reduction in intensity of the carboxylate peaks of alginate and the peak at 1058 cm?1, present in the FTIR of the matrices, is shifted to lower wave-numbers in the formulations, signifying interactions between the formulation components that make for good slow release. The DSC thermograms of all formulations showed evidence of interaction of imazaquin carboxylate group with the N-atoms of the macromolecules, which is indicative of reduced crystallinity of imazaquin.
Adsorption of Fluoride from Aqueous Solution Using Low-Cost Bentonite/Chitosan Beads  [PDF]
Yi Zhang, Dongfeng Wang, Bingjie Liu, Xiang Gao, Wei Xu, Peng Liang, Ying Xu
American Journal of Analytical Chemistry (AJAC) , 2013, DOI: 10.4236/ajac.2013.47A007
Abstract:

A new adsorbent namely bentonite/chitosan beads has been synthesized and studied for its defluoridation efficiency. Bentonite was activated and the beads were prepared using the inverse suspension polymerization method. The bentonite/chitosan beads (bentonite dosage of 3.0 g) showed an adsorption capacity of 0.895 mg/g whereas chitosan beads had only 0.359 mg/g. The optimal pH value was observed at pH 5 where the adsorbent reached the maximum defluoridation capacity of 1.164 mg/g. The effect of temperature, contact time and initial fluoride concentration on the adsorption capacity of the adsorbent has also been investigated. Scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX) and Fourier-transform infrared spectrometry (FTIR) were used to characterize the adsorbent. The adsorption of fluoride onto the adsorbent followed Freundlich isotherm model and pseudo-second order kinetic model. The fluoride loaded adsorbent could be regenerated using sodium hydroxide.

Study of the Adsorption Efficiency of an Eco-Friendly Carbohydrate Polymer for Contaminated Aqueous Solution by Organophosphorus Pesticide  [PDF]
Z. Abdeen, Somaia G. Mohammad
Open Journal of Organic Polymer Materials (OJOPM) , 2014, DOI: 10.4236/ojopm.2014.41004
Abstract:

The removal of pesticide (ethoprophos) from aqueous solution using a natural biosorbent such as chitosan (CH) prepared from a biopolymer waste obtained from marine industry was studied. The Fourier Transform Infrared Spectroscopy (FTIR), Scanning electron microscopy (SEM), and X-ray diffraction spectroscopy (XRD) were used to study the structure of the adsorbent. The biosorption studies were carried out under various parameters, such as biosorbent dose, initial pesticide concentration and contact time. The experimental results show that the removal percentage of ethoprophos increased from 85.693% to 89.234%, as adsorbent dose (CH) increased from 0.02 to 0.1 g/100ml. The equilibrium uptake was increased with an increase in the initial pesticide concentration in solution. Biosorption kinetic data were fitted well with the pseudo-second order kinetic model. The experimental isotherms data were analyzed using Freundlich, Langmuir, Temkin and Dubinin-Radushkevich (D-R) isotherm equations. The best fit was obtained by Freundlich isotherm with high correlation coefficients. That the value of energy calculated from the D-R isotherm was 5.56 KJ/mol suggests the adsorption of ethoprophos on Chitosan is physical. All the results indicating CH was chosen as low-cost biosorbent could be applied for the removal of organophosphorous pesticide from aqueous solutions.

Características e propriedades de quitosanas purificadas nas formas neutra, acetato e cloridrato
Signini, Roberta;Campana Filho, Sérgio P.;
Polímeros , 2001, DOI: 10.1590/S0104-14282001000200007
Abstract: commercial chitosan is purified in the neutral form and as chitosan acetate and chitosan hydrochloride. these samples were characterized and compared with respect to solubility, hydrophilicity, surface's morphology and crystallinity. commercial chitosan and its neutral purified form present similar characteristics and properties but the saline purified forms, mainly the chitosan hydrochlorides, are quite different from them. the surface morphologies of the former samples are similar but that of the lyophilized chitosan hydrochloride presents pores which are not observed in the other samples. commercial chitosan and its neutral purified form are not soluble in pure water but chitosan acetate is partially soluble. these samples present similar hydrophylicities and crystallinities but in the cases of the chitosan hydrochlorides the presence of charges and of counter ions from a strong acid enhances the hydrophilicity, promotes solubility in water and significantly alters the interactions inter and intrachains, modifying the packing in the solid state and drastically reducing the crystallinity. in the case of chitosan acetate it is observed that the crystallites are smaller probably due to the partial protonation of amine groups and to the presence of acetate anions.
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