Natural pterostilbene grafted Chitosan for fabricating a durable antibacterial cotton fabric through layer-by-layer assembled coating

Natural antibacterial agents exhibit tremendous potential in fabricating the durable antibacterial fabrics. Herein, natural pterostilbene (PL) was grafted onto chitosan (CS) through a Mannich reaction to obtain PLCS with high antibacterial activity. Furthermore, the durable antibacterial cotton fabric was fabricated using a layer-by-layer assembled coating with PLCS as the antibacterial agent. The results showed that at a molar ratio of PL to CS of 0.2:1 and a temperature of 80 ℃, PLCS with a grafting ratio of 17.3% achieved the lowest minimum inhibitory concentrations of 33.2 and 16.6 µg/mL against Staphylococcus aureus ( S. aureus ) and Escherichia coli ( E. coli ), respectively. Compared to those of CS and PL alone, the antibacterial activity of PLCS against S. aureus improved by 67.0% and 58.5%, while the activity against E. coli improved by 94.8% and 44.7%, respectively. The antibacterial rate of the PLCS cotton fabric against S. aureus and E. coli reached up to 99.9% after three assembled layers and maintained more than 80% after 20 washings. The PLCS antibacterial fabrics exhibited good wearing safety and wearing performances.