Formulation of hybrid nanocomposites based on silver nanowires on graphene surface for the fabrication of SERS substrates

his work is aimed at finding optimal formulations of silver nanowires (AgNWs) and graphene derivatives, including proper assembly and engineering in 2D hybrid substrates, to define a standard, simple and reproducible procedure for surface-enhanced Raman spectroscopy (SERS) detection of proteins. AgNWs (5±3 ?m in length, 48±10 nm in diameter) were synthesized by the chemical reduction method of silver nitrate (AgNO3) in ethylene glycole (EG) and polyvinylpirrolidone (PVP), according to Hu et al.[1] with few changes. The reaction has been optimized in order to obtain a good yield of nanowires and good reproducibility. AgNWs were characterized by Scanning electron microscope (SEM) and UV-Vis spectroscopy. The synthesized AgNWs were assembled to obtain a 2D array to provide a random homogeneous distribution. Aerosol deposition was selected as simple and very low-cost method to fabbricate dot array AgNWs SERS substrates. In this study hybrid nanocomposite, obtained by the depositon of AgNWs on graphene nanoplatlets-based paper (G-PAPER), were compared with an array of AgNWs on Polytetrafluoroethylene (PTFE) membrane[2], according the same deposition condition. The as-fabricated substrates were first characterized by atomic force microscopy (AFM), and secondly were analyzed under a microRaman spectrometer to test their optical response. Finally, selected substrates were used for direct detection of myoglobin as reference protein, upon simple deposition of few-microliter drops of solution on the top of the substrate followed by evaporation and Raman inspection. The as-obtained spectra showed comparable SERS profile. Furthermore, we observed a substantial improvement in signal-to-noise ratio with quenching of fluorescence background in the hybrid SERS substrate.