The Fabrication and Detection Performance of High Sensitivity Au-Ag Alloy Nanostar/Paper Flexible Surface Enhanced Raman Spectroscopy Sensors

Au-Ag alloy nanostars based flexible paper surface enhanced Raman spectroscopy sensors were fabricated through simple nanostar coating on regular office paper, and the surface enhanced Raman spectroscopy detection performances were investigated using crystal violet dye analyte. Au-Ag nanostars with sharp tips were synthesized via metal ions reduction method. Transmission electron microscope images, X-Ray diffraction pattern and energy dispersive spectroscopy elemental mapping confirmed the nanostar geometry and Au/Ag components of the nanostructure. UV-Vis-NIR absorption spectrum shows wide local surface plasmon resonance induced optical extinction. In addition, finite-difference time-domain simulation shows much stronger electromagnetic field from nanostars than from sphere nanoparticle. The effect of coating layer on Raman signal intensities was discussed, and optimized 5-layer coating with best Raman signal was obtained. The Au-Ag nanostatrs homogeneously distribute on paper fiber surface. The detection limit is 10-10 M, and the relationship between analyte concentrations and Raman signal intensities shows well linear, for potential quantitative analysis. The calculated enhancement factor is 4.795x106. The flexible paper surface enhanced Raman spectroscopy sensors could be applied for trace chemical and biology molecule detection.