Multifunctional modification of bio–based polyamide 56 fabric via luteolin for durable colouristic, antioxidant, antibacterial and UV protective properties

Natural extracts, characterized by their superior biocompatibility and multifunctionality, have demonstrated remarkable potential in fields such as antibacterial, antioxidant and ultraviolet (UV) protection. However, at present, natural extracts are facing a key bottleneck in functional finishing—poor washing durability. In this study, luteolin, a natural extract, was chosen to treat bio-based Polyamide 56 (PA56) fabrics. The findings indicated that the fabric dyed with luteolin not only achieved good coloration but also exhibited outstanding multi-functional properties: the ultraviolet protection factor (UPF) value reached 205, the ABTS radical cation (ABTS •+ ) scavenging rate was 99 %, and the antibacterial rates against Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ) were 70 % and 95 %, respectively. To further enhance the color fastness and functional durability, this study introduced metal ions. Through the coordination reaction between luteolin, metal ions and PA56, the color fastness was successfully raised to level 4 or above, and the durability of functionalities was significantly improved. After 10 washing cycles, the UPF value of the fabric remained at 155, the ABTS •+ scavenging rate exceeded 60 %, and the antibacterial rate against S. aureus remained at 75 %. This study proposed and verified a sustainable and coordinated strategy based on coordination chemistry, systematically addressing the durability issue of natural functional finishing agents.