Flexible silver nanoparticle@aramid nanofiber SERS substrates fabricated by radio frequency magnetron sputtering for rapid detection of toxic substances

Aramid nanofibers (ANFs) have gained great interest as promising polymer substrates for various applications because of their exceptional mechanical properties, high aspect ratio, large specific surface area and excellent chemical and thermal stability. However, the use of ANFs as nano-sized functional substrates for surface-enhanced Raman scattering (SERS) sensing applications has been scarcely reported. In this research, ANF membranes fabricated by vacuum-filtration are served as SERS matrix materials. The silver nanoparticle-coated ANF (AgNP@ANF) membranes are fabricated by a facile, cost-effective, environmental-friendly, and scalable magnetron sputtering technique. Different sputtering times from 15 to 120 s have been studied for AgNP@ANF substrates in terms of their SERS performance. The optimal AgNP-90@ANF SERS substrate exhibits good detection sensitivity of 10−10 M for malachite green (MG), high enhancement factor of 7.7×108 and prominent signal reproducibility (RSD=5.87%), as well as impressive storage stability. Furthermore, the AgNP@ANF SERS substrates also demonstrated excellent detection capability for methylene blue and crystal violet, with sensitivities of 10−10 and 10−9 M, respectively. Besides, the flexible AgNP@ANF SERS substrate can also be used to rapidly detect pesticide residues on uneven surfaces through a facile paste-and-read treatment. The simple-to-manufacture, inexpensive, scalable, and sensitive AgNPs@ANF sensors are very promising for commercial SERS applications in the future.