فهرست نشریات علمی دسترسی آزاد ایران

The textile industry seeks sustainable alternatives to synthetic dyes and antimicrobial agents. This study introduces a novel synergistic platform on wool textiles by harnessing natural indigo dye not only as a colorant but also as a bioreductant for the in situ synthesis of silver nanoparticles (AgNPs). The primary novelty lies in the creation of a controlled, dual-phase antimicrobial system (Ag⁰/Ag⁺) directly on the fiber, a mechanism absent in conventional finishing. Polyphenolic compounds inherent to plant-derived indigo selectively reduced silver ions, yielding a combination of metallic Ag⁰ nanoparticles for sustained release and residual Ag⁺ ions for immediate bactericidal action. This dual-phase system was confirmed by XPS analysis, revealing a controlled speciation of 75-80% Ag⁰ and 20-25% Ag⁺. The combined treatment exhibited genuine synergistic efficacy, as confirmed by a Synergy Index (SI) of 1.31-1.48 (p < 0.01), resulting in a greater than 99% reduction in bacterial growth (2.1-2.3 log) against S. aureus and E. coli. Furthermore, this work demonstrates that indigo’s π-conjugated aromatic structure facilitates coordination with silver species, enhancing nanoparticle adhesion. This was evidenced by FTIR peak shifts (1630→1620 cm⁻¹), resulting in superior wash fastness, with 82% of antimicrobial activity retained after 25 AATCC wash cycles, compared to 65% for AgNP-only treated wool. This green, one-pot functionalization approach offers a scalable strategy for producing high-performance, multifunctional textiles with durable, clinically grade anti-microbial properties for sustainable applications.