Antibacterial and physicomechanical properties of cellulosic nonwovens functionalized with chitosan: a study on interaction effects of influencing factors and assessment methods

The growing demand for antimicrobial textiles and environmental concerns over synthetic agents have driven interest in biobased agents like chitosan, an eco-friendly alternative reported with variable effectiveness on textiles. This research investigates the effects of chitosan's molecular weight, concentration, treatment method, and their interaction effects on the antibacterial and physicomechanical properties of cellulosic nonwovens. The role of culture medium dynamics in antibacterial testing was also examined. Chitosan with low (30 kDa), medium (250 kDa) and high (2100 kDa) molecular weights at concentrations of 1 to 15 g/L was applied using pad-dry and dip-dry methods, with dip coating resulting in higher chitosan deposition. Antibacterial activity against Escherichia coli (E. coli) was assessed using three methods: agar diffusion, a luminescent bacterial biosensor assay, and log reduction of colony-forming units (CFU/mL) in a time-kill test. While the first two test methods showed no antibacterial effect, CFU/mL revealed significant activity with interaction effects showing that the dip-coated, 30 kDa chitosan above a concentration of 5 g/L achieved complete bacterial reduction. The enhanced antibacterial performance of chitosan-coated cellulosic substrates, compared to chitosan in a culture medium, highlighted the role of cellulosic nonwoven in boosting antibacterial effectiveness, likely through improved contact and interaction with bacterial cells. The study demonstrated that chitosan-treated cellulosic nonwovens, particularly with dip-dry coating altered tensile strength and increased the bending resistance and bending stiffness.