Separation and Identification of Nanoplastics via a Two-Phase System Combined with Surface-Enhanced Raman Spectroscopy

Nanoplastics, novel environmental pollutants widely dispersed, present challenges due to limited, dependable detection methods, particularly for trace levels. This study introduces a novel approach that integrates liquid-phase self-assembly nanoparticle technology with surface-enhanced Raman spectroscopy (SERS) for the precise detection of nanoplastics. Utilizing hydrophobic–lipophilic interactions and SERS technology, we developed silver nanoparticles (Ag NPs)@poly(methyl methacrylate) (PMMA) films (Ag NPs@PMMA films) for the efficient extraction and simultaneous detection of polystyrene (PS) and polyethylene terephthalate (PET) nanoplastics at extremely low concentrations (e.g., 10–11 mg/mL for 20 nm PS nanoplastics and 10–8 mg/mL for 70 nm PET nanoplastics). It also demonstrates a linear correlation between SERS intensity (y) and the logarithm of nanoplastics’ concentration (lg c) at extremely low levels. This technique’s applicability extends to real environmental samples, such as seawater, oysters, and bottled water, enabling both qualitative and quantitative detection of PS and PET nanoplastics. For example, it successfully identifies 1.23 × 10–10 mg/mL PS nanoplastics in seawater samples and 8.61 × 10–5 mg/mL PET nanoplastics in bottled-water samples. Overall, these findings provide a reliable basis for trace nanoplastic detection in the environment, addressing a pressing environmental concern.