Optimization by 2D mapping of the Surface-Enhanced Raman Spectroscopy of methylene blue using silver nanowires
The parametric behavior of the Surface-enhanced Raman Spectroscopy (SERS) intensity and its enhancement mechanisms were investigated using methylene blue (MB) as SERS probe and silver nanowires (AgNWs) as SERS substrate. The AgNWs were synthesized in ethanol solution via electroless deposition. The AgNWs were deposited on glass slides via the Doctor Blade method, while MB was drop-coated on the AgNW substrate. A 5x4 map was obtained by mapping the AgNW volume versus the MB concentration. Each sample was characterized by Raman microscopy. The Raman scattering was found to be enhanced by a magnitude of 10, while MB peaks were observed to have red-shifted which indicates the chemical enhancement. With constant AgNW volume, the SERS intensity increased linearly with the MB concentration. With constant MB concentration, the SERS intensity saturated at the 150 μL volume due to the frequent addition of the AgNWs. The response surface plot of the SERS intensity was obtained by interpolation, and it was found to peak at 425 μM MB and 156 μL AgNWs. These parameters were found to be the optimum SERS enhancement condition for molecule detection.