O,N-carboxymethyl chitosan-zinc complex: A novel chitosan complex with enhanced antimicrobial activity

Chitosan is a biodegradable, biocompatible and non-toxic deacetylated derivative of chitin. It exhibits myriad of biological activities such as antithrombogenesis, anti-tumor activity, antimicrobial activity, wound healing activity and blood compatibility. Due to the presence of amine (-NH2) groups and hydroxyl (-OH) groups, chitosan can be modified to generate various novel derivatives with varying solubility patterns. Among the various derivatives, O,N-carboxymethyl chitosan has been found to elicit broad range of biological activities and proved to be useful in pharmaceutical applications. Chitosan derivatives form co-ordinate complexes with metal ions like zinc and copper which are also known to have antimicrobial activity. In the present investigation, O,N-carboxymethyl chitosan-zinc complex and chitosan-zinc complex were prepared and characterized using FTIR, XRD and DSC. Further, the complexes were evaluated and compared for antimicrobial activities against Gram-positive and Gram-negative bacteria. The studies revealed that the proposed novel O,N-carboxymethyl chitosan-zinc complex exhibited better antimicrobial activity than chitosan-zinc complex. (C) 2011 Elsevier Ltd. All rights reserved.