Deep Eutectic Solvent-Assisted Synthesis of Au Nanostars Supported on Graphene Oxide as an Efficient Substrate for SERS-Based Molecular Sensing

The development of hybrid nanostructures of graphene oxide (GO) and metal nanoparticles (NPs) is of paramount interest for highly flexible surface-enhanced Raman scattering (SERS) substrate-based molecular sensing. In this work, we report a simple and eco-friendly synthesis strategy for the synthesis of a three-dimensional (3D) GO/gold nanostar (3D GO/Au NS) hybrid nanocomposite using deep eutectic solvent (DES) for SERS-based molecular sensing. The 3D GO/Au NS hybrid nanocomposite was obtained by a two-step synthetic process. In the first step, the GO nanosheets of thickness ∼1.25 nm were homogeneously dispersed in choline chloride/urea (molar ratio of 1:2)-derived DES, followed by functionalization of −NH groups using 3-aminopropyltriethoxysilane. Afterward, the presynthesized Au NSs of size ranging between 150–200 nm were then covalently attached on the −NH-functionalized GO nanosheets mediated by DES at 60 °C to obtain 3D GO/Au NS hybrid nanocomposites. Importantly, the SERS substrate fabricated using...