Trapping and Detecting Nanoplastics Using Metal–Phenolic Networks–Functionalized Membranes with SERS

The widespread production and disposal of plastics pose severe risks to human health and ecosystems, primarily due to the likelihood of degradation into microplastics and/or nanoplastics, which increases the probability of exposure. Traditional detection methods for these particles are often hindered by limitations in sensitivity, cost, and labor intensity of performing the analyses. Hence, our study presents a novel approach utilizing metal-phenolic networks (MPNs)-functionalized membranes combined with surface-enhanced Raman spectroscopy (SERS) for the rapid trapping and sensitive detection of polystyrene nanoplastics (PSNPs). By integrating MPNs with nitrocellulose membranes, this method can effectively trap diverse sizes of PSNPs (1 μm, 500 nm, and 50 nm) with >90% trapping efficiency and enable the sensitive SERS detection of small-sized 50 nm nanoplastics at concentrations as low as 0.1 mg/L. Quantitative analysis demonstrated a strong linear relationship between PSNPs concentration and SERS intensity, facilitating accurate monitoring in real-world samples. Notably, the method achieved a high recovery rate of >90% for the analysis of 50 nm PSNPs (10 mg/L, 1 mg/L, 0.1 mg/L) in tap water, along with a trapping efficiency >90% across different PSNP concentrations: 10 mg/L, 1 mg/L, 0.1 mg/L. These results show that the MPNs-functionalized membrane coupled with SERS provides a promising platform for effectively trapping and sensitively detecting nanoplastic contaminants in environmental systems. This innovative approach offers significant advantages over conventional methods, including low cost, user-friendliness, and practicality for effective trapping and on-site detection of nanoplastics.