Synthesis and characterization of novel trimellitic anhydride isothiocyanate-cross linked chitosan hydrogels modified with multi-walled carbon nanotubes for enhancement of antimicrobial activity

Novel trimellitic anhydride isothiocyanate was successfully synthesized and utilized in various concentrations to obtain four novel cross linked chitosan hydrogels H-1-H-4. Three multi-walled carbon nanotube (MWCNT) biocomposites based on H-1 were also prepared. Their structures were proven by elemental analysis, FTIR, XRD, SEM and TEM. They were found to be pH- and temperature-responsive materials. Their swell abilities appreciably depend on their cross linking moiety contents and MWCNTs concentration. They are more potent against Bacillis subtilis, Streptococcus pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Geotrichum candidum, Candida albicans, Aspergillus fumigatus, and Syncephalastrum racemosum than chitosan as judged by their greater inhibition zone diameters and their lower minimum inhibitory concentration (MIC) values. Their antimicrobial activities increased with increasing their cross linking moiety contents. They showed a better potency against Gram-positive than Gram-negative bacteria. The hydrogel H-4 and H-1/MWCNT composites have comparable or even higher activities than the reference bactericides or fungicides against some of tested microbes. Thus, combination between chitosan and the functionalized groups of the incorporated cross linker as well as MWCNTs in one system has efficiently improved the chitosan features. It is a good way for attaining adequate systems as antimicrobial agents that can be taken as promising candidates in biomedical fields. (C) 2019 Elsevier B.V. All rights reserved.