Antimicrobial oxidized hemp fibers with incorporated silver particles

Abstract

In this study, antimicrobial silver-loaded hemp fibers were prepared by selective TEMPO-mediated oxidation, i.e., oxidation with sodium hypochlorite, catalytic amount of sodium bromide and the 2,2,6,6-tetramethylpiperidine- 1-oxy radical (TEMPO), followed by silver sorption from aqueous silver nitrate solution. The most suitable experimental conditions for the selective TEMPO-mediated oxidation were determined by changing the oxidation conditions, i.e., the concentration of sodium hypochlorite and the duration of oxidation. The obtained results showed that the maximum sorption capacity of 0.703 mmol of silver per gram of modified hemp fibers was obtained for the sample oxidized with 9.67 mmol NaClO per gram of fibers for 4 h. SEM Microphotographs of the modified hemp fibers with incorporated silver showed uniformly distributed silver particles on the surface of fibers, with isometric shapes and sizes from 10 to 100 nm, despite the fact that silver was sorbed from an ionic solution. The antibacterial activity of the TEMPO-oxidized hemp fibers with silver particles was confirmed in vitro against two strains: Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922), and the antifungal activity against Candida albicans (ATCC 24433). The best antimicrobial activity of silver-loaded TEMPO-oxidized hemp fibers was showed against strain S. aureus.