Hydrogen Bonding-Based SERS Method for the Ultrahigh-Sensitive Detection of Nanoplastics in Water

Surface-enhanced Raman spectroscopy (SERS) has emerged as a promising analytical tool for environmental risk assessment in recent years. However, it is still a challenge to achieve ultrahigh sensitive detection of nanoplastics. Herein, we propose a hydrogen bond-driven strategy for the ultratrace detection of polystyrene (PS) nanoplastics. With cysteine (Cys) modified, the silver nanoparticle (Ag NP) surface background interference can be removed. Depending on the intermolecular hydrogen bond between Cys and PS, Ag NPs can be effectively attached to PS to provide abundant hot spots. Thus, highly sensitive detection can be achieved for PS in the range of 50-800 nm with a detection limit as low as 50 ng L-1 and a linear dynamic range spanning 2-3 orders of magnitude. In spike-and-recovery experiments utilizing tap water, standard PS demonstrates recoveries ranging from 86.7% to 106.6%. Moreover, PS isolated from packaging materials exhibited a mass concentration of 3 mg L-1 consistent with commercial nanoparticle tracking analysis. The proposed strategy demonstrates ultralow detection limits, expected accuracy, and a broad linear range, thereby providing a novel analytical framework for monitoring nanoplastics contamination in water.