Citric acid mediated chitosan oligosaccharide-Zn (II) co-modified cotton textiles with prominent antibacterial and antiviral performance

Cotton textiles (CTs) with antibacterial and antiviral activity are of great concern due to the needs of the health and hygiene fields. Herein, chitosan oligosaccharide (COS) and divalent zinc ion Zn (II) were innovatively introduced onto the CTs via esterification and coordination reaction initiated by citric acid (CA) and enabled the CTs with prominent antibacterial and antiviral activity ( Escherichia coli : 100 %, Staphylococcus aureus: 100 % , MS2: 99.9 %). The individual COS and Zn (II) modified CTs showed limited antibacterial performance; only concentrated zinc chloride (at least 10 %) treatment could enable the CTs to have a comparative effect with that of the combined treatment of the COS and Zn (II) (1 %). The sequential COS modification and zinc chloride (2 %) treatment was proved to be the optimum because of the 100 % bacterial inhibition rate benefitting from the dual antibacterial and antiviral mechanism originating from COS and Zn (II). The post treatment with excessive zinc chloride could shift the antibacterial mechanism from the dual to the individual action and therefore postponed to inhibit bacterial propagation. More importantly, the post Zn (II) modification could compensate for the strength loss of cotton cloth caused by the acidic degradation of cellulose. The co-modification affects the color and hydrophobicity of the CTs significantly other than the properties of toughness, softness, slipperiness, and drapeability. This strategy has the advantages of an eco-friendly and simple process, which is a good choice for preparing safe, economical, and efficient antibacterial and antiviral CTs.