Portable surface-enhanced Raman scattering platform for rapid identification of nanoplastics at single-particle level

Plastic food packaging and containers release micro- and nanoplastics during use and may therefore pose health risks. However, the current methods of plastic particle analysis are often time-consuming and restricted to laboratory settings, which limits their real-sample applicability. Herein, we report a paper-based surface-enhanced Raman scattering (SERS) platform enabling the ultrasensitive and reproducible detection of plastic particles using a portable 785 nm Raman spectrometer. The SERS substrate is fabricated by thermally evaporating Au onto cellulose filter paper with controlled surface energy, forming a densely packed nanoparticle monolayer. Owing to the abundant plasmonic hotspots on the SERS substrate, this platform can detect micro- to nanosized polystyrene and nylon particles at the single-particle level. The platform has an enhancement factor (EF) of 2.3 × 10¹⁰, an extremely low limit of detection (LOD) of 1 ppt, and high reproducibility (relative standard deviation = 11.15 %) for 20 nm polystyrene. Moreover, the platform enables the parallel label-free detection of multiple plastic types while effectively minimizing interference from organic dyes. The practical utility of the developed platform is demonstrated by the detection of nanoplastics released from food containers and teabags under realistic conditions. These findings indicate the potential of the SERS detection system as a powerful field-deployable tool for assessing plastic contamination in complex real samples.