Surface charge-dependent toxicity of polystyrene nanoplastics in human lung epithelial BEAS-2B and HaCaT cells

The increasing use of plastic products has resulted in the release of nanoplastics (NPs), raising concerns regarding the potential impact on human health. Humans are continuously exposed to NPs through inhalation, ingestion, and dermal contact, yet direct evidence of adverse health effects remains limited. The aim of this study was to examine the cytotoxicity attributed to polystyrene (PS)-NPs with different surface charges-positively charged PS-NH₂-NPs, and negatively charged COOH-PS-NPs using as model human lung epithelial (BEAS-2B) and skin keratinocyte (HaCaT) cells. Confocal microscopy confirmed that all PS-NPs penetrated the cell membrane, indicating their potential for cellular interaction. Amongst the PS-NH₂-NPs induced the highest cytotoxicity in both cell types, suggesting a strong association between positive surface charge and cellular damage. In addition, exposure to PS-NH₂-NPs initiated a concentration-dependent increase in reactive oxygen species (ROS), indicative of oxidative stress as a key mechanism underlying toxicity. Data demonstrated that positively charged PS-NH₂-NPs pose a greater toxicological risk than neutral or negatively charged counterparts. Our findings indicate the significance of surface charge in determining NP-induced toxicity and contribute to a better understanding of their potential risks to lung and skin health. Further research is necessary to validate these findings and inform regulatory efforts for safer plastic material usage.