Biodistribution and toxicity analysis of polystyrene nanoplastics in mice based on Raman detection

This study employed surface-enhanced Raman spectroscopy (SERS) with mouse exposure models to investigate the deposition, biodistribution, and toxicity of polystyrene nanoplastics (PS-NPs; 20 nm, 100 nm, 1000 nm) in lungs. By adjusting the synthesis conditions, this study prepared Au@Ag nanorods with different silver shell thicknesses. An optimized Au@Ag nanorod substrate (8.5 nm Ag shell thickness) demonstrated high SERS activity, excellent reproducibility (RSD = 5.91 %). The lowest concentration of nanoplastics that can be detected by this substrate is 0.01 mg/mL, and the linear relationship is good (R² > 0.9). Based on this substrate, accurate and rapid detection of PS was achieved in water, serum, and even tissue samples. Following tracheal instillation exposure (7, 30, 90 days), smaller PS-NPs (20 nm, 100 nm) accumulated more in lungs and translocated more readily to liver and kidneys than 1000 nm particles. Smaller particles caused more severe lung histopathology and induced significantly greater oxidative stress (increased MDA, decreased GSH-Px/SOD) and inflammation (elevated CCL17, CXCL4, TNF-α), showing clear size dependence. This research is the first to use SERS to reveal the dynamic distribution and toxicity mechanisms of PS-NPs in lungs, confirming the high bio-penetration and potent toxicity of small nanoplastics. It provides critical data for assessing airborne nanoplastics respiratory risks and developing biomonitoring and prevention strategies.