Imparting durable antimicrobial properties to cotton fabrics using alginate–quaternary ammonium complex nanoparticles

A new type of nanoparticle composed of sodium alginate (SA) and 3-(trimethoxysilyl)propyl-octadecyldimethylammonium chloride (TSA) was prepared by ionic gelation. The average size of the SA–TSA nanoparticles was significantly affected by the initial mass ratio of SA and TSA used for the formation of the SA–TSA colloidal solution. SA–TSA nanoparticles with an average size of 99 nm were chosen and loaded onto cotton fabrics by a pad-dry-cure method. Scanning electron microscopy of the treated fabric indicated SA–TSA nanoparticles were well-dispersed on the fabric surface. Cotton fabrics treated with the nanoparticles at 70 ppm concentration demonstrated efficient antimicrobial activity (>99.99% reduction in viable cell counts) against a representative Gram-negative bacterium (Escherichia coli) and a Gram-positive bacterium (Staphylococcus aureus). The antibacterial efficacy was maintained even after 30 laundry cycles. The results indicate that the SA–TSA nanoparticles can be useful as a non-leaching agent imparting durable antimicrobial properties to cotton fabrics.