Antimicrobial and antioxidant properties of chitosan-based viscose fibres enzymatically functionalized with flavonoids

The main purpose of this research was to qualitatively and quantitatively identify chitosan-based viscose fibre functional group surfaces as modified by two chemically-similar phenolics, namely fisetin and quercetin. Potentiometric titration was used to determine fibre-dissociable weak acids as a consequence of the presence of chitosan and deposited flavonoids. In addition, a conventional spectrophotometric method using C.I. Acid Orange 7 dye was used for determining the amino groups only. Finally, the antioxidant and antimicrobial properties of the fibres were evaluated, respectively. It has been clearly shown that the introduction of flavonoid onto the fibres introduces a significant amount of anionic phenolic hydroxyl groups, leading to fibre antioxidant activity and a decrease in fibre antimicrobial efficiency.