A novel real-time detection SERS method for rapid detection of marine nanoplastics via size-dependent combination analysis of Au@Ag-Polystyrene

As a global environmental concern, real-time detection of marine nanoplastics (NPs) has gained increasing attention. However, current detection methods are still confronted with the challenge of detecting low concentration NPs in marine solution conditions, and it is imperative to establish a rapid detection method for directly detecting NPs in marine solution. In this study, a silver coated gold nanoparticle (Au@Ag) based real-time SERS detection strategies is proposed, with a particular focus of the enhancement mechanism of the particle diameter for SERS performance. Compared with common SERS enhancing particles, Au@Ag demonstrates remarkable SERS enhancement capability. For mechanism investigation, particle diameter is a critical factor significantly influenced the signal intensity of testing specimen. Among all diameter combinations, SERS performance reaches the maximum level when the particle diameter of Au@Ag is slightly smaller than polystyrene nanoparticles (PS NPs). Under these conditions, the lowest detection concentration of PS NPs in purified water without any extra pretreatments was determined to be approximately 0.1 μg/mL. By employing the same PS NPs and Au@Ag in artificial seawater solution, the lowest detection concentration of PS NPs reaches to 0.01 μg/mL. These results indicate that the efficacy of Au@Ag for real-time SERS detection of PS NPs in marine solution, and provide a valuable reference for future study of material selection and particle size optimization for NPs in-situ SERS detection for real marine condition.