Facile Biosynthesis and Antioxidant Property of Nanogold-Cellulose Fiber Composite

Direct synthesis of gold nanoparticles (AuNPs) on cellulose fiber has been successfully performed via facile green approach using lignin-containing unbleached kraft softwood pulp. The resulting AuNPs composited fibers showed apparent color change from pale yellow to purplish-dark brown by varying the amount of gold ions (Au3+) due to the surface plasmon resonance of nanogold. Further confirmation of AuNP formation on the fiber surface was conducted by UV-Vis diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). X-ray photoelectron spectroscopy (XPS) analysis revealed that gold nanoparticles formed on the fiber are well-defined pure metallic gold, indicating that Au3+ ions are efficiently bioreduced into Au-0 and bind to the fiber surface. Antioxidant activity was evaluated by decomposition of 2,2-diphenyl-1-picryl-hydrazyl (DPPH) in dark and light condition. As-prepared unbleached kraft fiber-AuNP composite showed significantly enhanced antioxidant activity and its DPPH scavenging rate reached about 86.05%.