Chitosan-Stabilized Silver Nanoparticles for Antimicrobial Polyester Finishing by Exhaustion Dyeing: A Critical Assessment of Synthesis-to-Textile Transferability

Chitosan-stabilized silver nanoparticles are promising antimicrobial agents for textile finishing, but their direct transfer from colloidal synthesis to polyester fabrics is limited by nanoparticle deposition, dispersion stability, and fiber–particle interactions. This study evaluated three reported chitosan-assisted silver nanoparticle routes for antimicrobial polyester finishing by exhaustion dyeing. The Ag-containing systems were characterized by UV-Vis spectroscopy, dynamic light scattering, thermogravimetric analysis, X-ray diffraction, scanning electron microscopy coupled with energy-dispersive spectroscopy, atomic absorption spectroscopy, and qualitative antimicrobial assays. The NaBH4-assisted route showed the most defined plasmonic band, with λmax at 408 nm before freeze-drying and 400 nm after redispersion. DLS indicated large apparent hydrodynamic diameters before freeze-drying, which shifted from 439.8, 357.2, and 653.5 nm to 28.7, 29.8, and 38.1 nm after drying/freeze-drying and redispersion for M1, M2, and M3, respectively. XRD confirmed metallic silver mainly in M1 and M2, while SEM/EDS revealed low silver incorporation on polyester fabrics, with 0.69, 0.11, and 0.20 at.% Ag. PET-M3 showed the clearest antimicrobial inhibition and the highest operationally extracted silver. These results indicate that effective antimicrobial polyester finishing requires improved purification, dispersion control, quantitative antimicrobial validation, and nanoparticle–fiber anchoring.