Structural and antimicrobial properties of irradiated chitosan and its complexes with zinc

The aim of this research was to evaluate the structural and antimicrobial properties of irradiated chitosan and its complexes with zinc. Chitosan having a molecular weight (M-eta) of 220 kDa was exposed to gamma rays in dry, wet and solution forms. The chitosan-zinc complexes were prepared by varying the M-eta of chitosan and Zn content. Viscometeric analysis revealed a sharp decrease in the M-eta of chitosan irradiated in solution form even at lower doses compared with the dry and wet forms. X-ray diffraction patterns demonstrated variation in the crystallinity of chitosan upon exposure to gamma rays. The antibacterial response of the irradiated chitosan and its complexes against gram-positive and gram-negative bacteria demonstrated wide spectrum of effective antimicrobial activities, which increased with the dose. Additionally, the complexes exhibited excellent antifungal activity with no growth of Aspergallious fumigatus and Fusarium solani even after two weeks. These results suggested that the irradiated chitosan and its complexes with Zn can be used as antimicrobial additives for various applications. (C) 2013 Elsevier Ltd. All rights reserved.