Construction of dense plasmonic hotspots on coarse Ag layer coated nylon fibers for ultrasensitive SERS sensing

Surface-enhanced Raman scattering is a powerful sensing tool effectively and rapidly to detect chemicals in environmental monitoring and food safety. Textile fiber-based surface-enhanced Raman scattering substrates have been fabricated to contribute to the practical applications of surface-enhanced Raman scattering sensing. Inspired by the metallic nanostructures with dense plasmonic hotspots which have excellent surface-enhanced Raman scattering activity, coarse silver layer coated nylon fibers are used in this study to combine with gold nanoparticles by a simple immersion method forming enriched plasmonic hotspots on textile fibers for ultrasensitive surface-enhanced Raman scattering detection. The fiber-based surface-enhanced Raman scattering substrate denoted as gold nanoparticle@silver layer coated nylon fiber shows a high sensitivity to rhodamine 6G with an excellent enhancement factor of 2.41 × 10 10 and a detection limit of 10 −14 M. The finite-difference time-domain simulations indicate that ultra-high sensitivity arises from the enhanced electric fields densely formed in the inter-particle and particle-film gap in the twisted gold nanoparticle@silver layer coated nylon fiber structure. In addition, the gold nanoparticle@silver layer coated nylon fiber substrate demonstrates outstanding surface-enhanced Raman scattering signal reproducibility (relative standard deviation 6.14%) as well as application flexibility. Through a simple swab procedure, gold nanoparticle@silver layer coated nylon fibers absorb rhodamine 6G molecules on apple and the detection limit can reach 10 −13 M. Our results allowed us to foresee the use of synthetic fibers enriched with plasmonic hotspots in ultrasensitive wearable sensors.