Silver-loaded lyocell fibers modified by tempo-mediated oxidation

The purpose of this research was to accomplish antimicrobial properties in lyocell fibers by Ag⁺ ions sorption from aqueous silver nitrate solution. Sorption properties of lyocell fibers were improved by the selective TEMPO-mediated oxidation, i.e. oxidation with sodium hypochlorite and catalytic amount of sodium bromide and 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO). The most suitable experimental conditions for the selective TEMPO-mediated oxidation were determined by changing oxidation conditions: concentration of sodium hypochlorite, as well as duration of sorption. The obtained results showed that the maximum sorption capacity (0.809 mmol of Ag⁺ ions per gram of fibers) of modified lyocell fibers was obtained for the sample modified with 4.84 mmol NaClO per gram of cellulose, during 1 h. The antifungal activity of the TEMPO-oxidized lyocell fibers with silver ions against fungi from the Candida family, Candida albicans (ATCC 24433), and antibacterial activity against two strains: Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922) were confirmed in vitro.