Multi-functional regenerated cellulose fibers decorated with plasmonic Au nanoparticles for colorimetry and SERS assays

Multi-functional cellulose fiber-Au composites were fabricated through a simple and cost-effective procedure by decorating regenerated cellulose fibers with Au nanoparticles. The cellulose fibers were regenerated from waste paper through the Ioncell-F process, an environmental friendly approach. After grafting positive charge, the surface of the cellulose fibers were decorated with citrate-stabilized plasmonic Au nanoparticles (NPs). X-ray photoelectron spectroscopy, scanning electron microscopy, X-ray diffraction, and optical images were used to characterize the regenerated cellulose fibers and fiber-Au NP composites. The fiber-Au composites exhibited different colors as the localized surface plasmon resonance property of Au NPs, which enables visual sensing of the water content in the fiber-Au composites through a colorimetric method. Furthermore, the regenerated cellulose fiber-Au composite was used as an enhanced substrate for the sensing of malachite green via surface-enhanced Raman scattering, in which the limit of detection was lower than 10 ppb. The multi-functional cellulose fibers are potentially suitable for the detection of toxins and the monitoring of water quality.