Antimicrobial finish of cotton fabrics treated by sophorolipids combined with 1,2,3,4-butanetetracarboxyic acid

Sophorolipids (SLs) are surface active glycolipids produced by nonpathogenic yeasts, and a combination of SLs with 1,2,3,4-butanetetracarboxyic acid (BTCA) was used as a new durable antimicrobial treatment method for cotton fabrics. The factors influencing the antibacterial property of the fabrics in the finishing process, such as the amount of SLs, treatment temperature, curing time, amount of BTCA, and sodium hypophosphite (SHP) were investigated. An optimized procedure for treating fabrics was two dips and two nips with a wet pickup of 90% in an aqueous solution containing 20 g/L of SHP, 40 g/L of SLs and 90 g/L of BTCA, then drying at 100 degrees C for 2 min and curing at 120 degrees C for 2 min. As a result, 99% of the S. aureus in a concentration of 3.0x10(4) CFU/mL were killed by the treated fabrics in 1 h contact according to ASTM Standards E2149-10, and the functions are durable against washing. The mechanism of BTCA crosslinking lactonic sophorolipid onto cellulose was investigated by using computational chemistry and experimental methods. As a non-irritant surfactant, sophorolipids proved to be a potential natural antimicrobial agent for textiles or medical products. Graphic abstract