Dopamine-mediated self-assembled anisotropic Au nanoworms conjugated with MoS2 nanosheets for SERS-based sensing

Abstract

Surface-enhanced Raman scattering (SERS) utilizing plasmonic metals coupled with transition metal dichalcogenide (TMD) has received increasing attention in bio-applications due to the synergistically enhanced detection sensitivity. However, there have been several issues to be addressed such as strong SERS background signals and low Raman intensities of analytes. In this study, we report a novel approach for high SERS performance based on anisotropic hybrid plasmonic nanostructures of gold nanoworms (Au NWs) conjugated with 2D Molybdenum disulfide (MoS2) nanosheets. To significantly enhance the SERS enhancement factor (EF), we optimized the gap between Au NWs and MoS2 to ~2 nm by controlling the thickness of polydopamine (PDA). Thus, giant localized electric field enhancement and synergistic coupling effect occurred in the hybrid plasmonic nanostructures, generating abundant hot spots. Consequently, SERS EF of the order of ~107 was achieved, which was 104 times higher than that of colloidal Au nanoparticles. Further, we showcase that our AuNW@MoS2 can detect the 10−10 M level thiram, a typical pesticide, under soil-pollutant muddy condition, evidencing the powerful multimodal sensory platform of our hybrid substrates. This work provides new insight into the rational design of plasmon-coupled 2D nanohybrids for high-performance SERS substrates with a premise for the practical and viable biosensing applications.