Metal ion-coordinated carboxymethylated chitosan grafted carbon nanotubes with enhanced antibacterial properties

Abstract

Covalent bonding of multiwalled carbon nanotubes (MWCNTs) with carboxymethyl chitosan (CmCs) was prepared by the grafting method. The reaction products were confirmed by Fourier transform infrared spectroscopy (FTIR). The transmission electron microscopy (TEM) images and the thermogravimetric analysis (TGA) showed that the MWCNTs were coated by the CmCs uniformly, and the solubility and stability of the composites also increased in dimethyl sulfoxide (DMSO) and aqueous solutions. Multiwalled carbon nanotubes (MWCNTs) with carboxymethyl chitosan (CmCs) composites have been prepared in this work. It has been found that MWCNTs were coated by the CmCs uniformly and the solubility and stability of the composites also increased in dimethyl sulfoxide (DMSO) and aqueous solutions. The Cu and Zn ions were further coordinated to the MWCNT–CmCs composites. The MWCNT–CmCs metal complex showed a slower release rate than the CmCs metal complex by conductivity measurements. The results have confirmed the coordinated MWCNT–CmCs exhibited excellent antibacterial activity against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli) and Vibrio anguillarum. The susceptibility of MWCNT–CmCs–Cu against bacteria was more pronounced than that of MWCNT–CmCs–Zn, and all the complex materials illustrated more excellent antibacterial ability for S. aureus. The MWCNT–CmCs metals complex still illustrated good antibacterial property against S. aureus after 21 days. These results hinted that the composites possess great potential to be an alternative to other antifouling agents.