Taking Advantage of Invasive Eupatorium adenophorum Plant for Eco-Synthesis and Stabilization of Nanosilver towards Durably Coloristic and Bioactive Silk Materials

Abstract

Recently, a growing emphasis has been placed on taking advantage of invasive plants for fabricating value-added and functional materials. In the present study, an easy and efficient approach to developing durably coloristic, antioxidant and antimicrobial silk using silver nanoparticles (AgNPs) prepared with the extract of an invasive weed—Eupatorium adenophorum (EA)—which plays dual roles of bio-based reductant and stabilizer. The impact of factors including pH, concentration of EA extract (EAE) and Ag+ ions, temperature and time during AgNPs synthesis against the nanoparticle size and distribution, and the AgNPs concentration, were explored. The relationship between the color feature of silk and the treatment conditions was investigated through a central composite experimental analysis. Finally, the antioxidant and antimicrobial activities as well as the washing durability of the AgNPs-decorated silk were demonstrated. The results revealed that the size of AgNPs also decreases when pH ranges from 7.7 to 10.1. The zeta potential of AgNPs is −18.3 mV due to the existence of EAE on the surface of AgNPs. AgNPs generated efficiently within first 30 min, and then slowed down from 30 to 60 min. Based on the mathematical modeling study, a theoretical highest KS of 6.95 is able to be obtained using the processing condition of AgNPs/EAE conc. 2.32 g/L; pH 2.65, temperature 68.6 and time 42.6 min. The silk decorated with AgNPs/EAE killed over 95% of E. coli and S. aureus within 24 h. The superb antimicrobial activity of the AgNPs-treated silk is contributed by the AgNPs that enable the microbial cell membrane damage and segmentation. After 30 times repeated washing, the antimicrobial activity of the treated silk still remained over 85% against both strains. In all, the functionalization of silk established in this work not only reduces the ecological destructions and economic losses induced by EAE, but also permits the obtaining of sustainably developed value-added, safe and functional textiles.