الفهرس 
Antimicrobial properties of chitosanOnly 14 pages are availabe for public view
 |  | from | 262 |  |  |
| | | from | 262 | | |
Abstract
Chemical modifications of chitosan (Cs) and carboxymethyl chitosan (CMCs) in absence and in presence of silver nanoparticles have been performed; the products were characterized, and then evaluated as antimicrobial agents. The first type of modification was attained by the reaction of Cs (CMCs) with various types of aldehydes to obtain the corresponding chitosan/Schiff-base/AgNPs derivatives. The aldehydes used in this modification are aliphatic, aromatic, and heterocyclic aldehydes as well as some prepared aldehydes of pyrazole derivatives. The second modification was obtained upon reactions of Cs(CMCs) with different carboxylic acids to get Cs(CMCs)/carboxylic acid adducts nanocomposites. Different carboxylic acids as monobasic, dibasic, aliphatic and aromatic acids were utilized to modify Cs (CMCs). characterization of the prepared compounds via elemental analyses and FT-IR spectroscopy confirmed the chemical structures of the products. SEM micrographs showed the homogeneity and the well distribution of AgNPs in the polymeric matrix, where TEM images showed that the size of the AgNPs ranged from 4 to 45 nm for all derivatives.TGA analysis revealed that the prepared compounds are characterized by good thermal stability. Water uptake determination of the prepared products was also carried out, and the results showed the affinity of the products to water swellability with different rates. Antimicrobial activities of modified Cs(CMCs)/silver nanoparticles against four pathogenic bacteria, two Gram +ve (Bacillus cereus and Staphylococcus aureus) and two Gram –ve (Escherichia coli and Pseudomonas aeruginosa), as well as the Candida albicans as a fungus
Abstract
2
were carried out. Results of antimicrobial activities of modified Cs (CMCs)/silver nanoparticles showed higher antimicrobial activity than Cs and CMCs, and all results were compared with the reference antimicrobial agents. The results of minimum inhibitory concentration (MIC) of the compounds under investigation were carried out and some of them exhibited high antibacterial effect, against the two types of Gram +ve and Gram –ve bacterial strains. Keywords: Chitosan, Carboxymethyl Chitosan, Chemical modification, Schiff bases, Thermal stability, Antimicrobial activity.