Deep Eutectic Solvent Ag Nanoparticle Plasmonic Platform for Sensing in Hydrophobic Media

Deep eutectic solvents (DES) are versatile solvents obtained by a mixture of components that results in a significant decrease in melting temperature. These systems have been widely described in the literature and can be suitable solvents for liquid–liquid extraction. Additionally, DES can be utilized in the synthesis media of metallic nanoparticles (NPs), allowing for control over growth, stabilization, and functionalization, while serving as an environmentally friendly alternative. In this study, we are merging the properties of DES as solvents and soft templates for nanomaterial synthesis to present an all-in-one sensing platform that extracts, preconcentrates, and probes species from hydrophobic analytical matrices such as margarine and oil. Through multivariate modeling, our approach achieved limits of detection on the order of 10–6 mol L–1 for the analyte extracted from margarine and oil. We demonstrate that DES-native NPs can be synthesized through a rapid procedure without the use of additional reducing agents, unlike other synthesis protocols. Also, the obtained NPs are highly stable against aggregation, making them suitable for both surface-enhanced Raman scattering (SERS) and plasmonic-colorimetric applications. Furthermore, the DES surrounding the NPs acts as an efficient extraction solvent, transferring the analyte from its matrix to the metal surface without the need for extra steps, thereby saving time and reagents in an entirely green procedure. Our results demonstrated that our approach can be easily optimized and customized, which, in the context of analytical SERS, circumvents one of its more challenging bottlenecks: performing SERS using colloidal NPs in hydrophobic media.