Single-nanoplastic detection based on plasmon-coupled scattering microscopy

The increasing presence of nanoplastics in aquatic environments has raised significant concerns due to their potential impact on ecosystems and human health. Traditional detection techniques face limitations in resolution, sensitivity, and cost-effectiveness, making the development of new methodologies essential. In this study, we introduce Plasmon-Coupled Scattering Microscopy (PCSM) as a novel approach for high-sensitivity detection and characterization of single nanoplastic particles. Unlike conventional Surface Plasmon Resonance techniques, which analyze bulk refractive index variations, PCSM enables localized detection of individual nanoparticles by leveraging plasmon-coupled scattering. This method was experimentally validated using polystyrene nanoparticles of different diameters, immersed in water over a gold thin film within a variant of the Kretschmann configuration. Theoretical modeling was performed using the T-matrix method, showing strong agreement with experimental results. This study demonstrates the technical feasibility of single-particle detection using PCSM under controlled conditions. Although it has not yet been applied to environmental matrices, the approach covers a broad particle size range (1–2500 nm) and is suitable for detecting commonly reported plastic pollutants. The method also shows potential for extension to other nanoscale water contaminants, supporting its future development as a versatile tool for environmental monitoring and pollution assessment. • Plasmon-Coupled Scattering Microscopy (PCSM) enables single nanoplastic detection. • Detection of individual 30 nm and 90 nm polystyrene nanoparticles is demonstrated. • Experimental results match well with theoretical modeling. • High angular sensitivity distinguishes materials with similar refractive indices. • PCSM offers broad potential for environmental nanoscale contaminant monitoring.