Iodine-loaded ZIF-7-coated cotton substrates show sustained iodine release as effective antibacterial textiles

Abstract

The increased antibiotic resistance of bacteria necessitates the development of novel solutions for the production of antimicrobial fabrics. In the current work, I₂@ZIF-7@cotton samples were successfully synthesized using a three-step process: (1) carboxymethylation of cotton fibers, (2) anchoring ZIF-7 onto modified cotton fiber surfaces via two procedures of reflux and layer-by-layer (LBL) methods (ZIF-7@cotton (1) and ZIF-7@cotton (2), respectively), and (3) iodine loading on ZIF-7@cotton samples. Then the ZIF-7@cotton and I₂@ZIF-7@cotton samples were fully characterized by FT-IR, PXRD, FE-SEM, TGA, ZP, and ICP analyses. The amounts of iodine adsorbed in the iodine-loaded ZIF-7@cotton samples (I₂@1 and I₂@2) were assessed by using TGA analysis (20.2 wt% and 21.2 wt%, respectively) and UV/vis spectroscopy (23.2 wt% and 24.9 wt%, respectively). Finally, the antibacterial activities of ZIF-7@cotton (1 and 2) and I₂@ZIF-7@cotton (I₂@1 and I₂@2) were investigated by a disk diffusion method against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. Four samples of ZIF-7@cotton (1 and 2) and I₂@ZIF-7@cotton (I₂@1 and I₂@2) inhibited only S. aureus bacterial growth significantly and the I₂@ZIF-7@cotton (I₂@2) sample showed the best performance in bacterial growth inhibition among the other prepared compounds.