Work

Are all nanoplastics equally neurotoxic? Influence of size and surface functionalization on the toxicity of polystyrene nanoplastics in human neuronal cells

Year: 2025

Type: article

Abstract: Nanoplastics (NPs) are an emerging environmental concern, particularly due to their potential interactions with the nervous system. We evaluated the neurotoxic effects of four types of polystyrene nanoplastics (PS-NPs): unmodified (plain) 50 nm and 100 nm particles, and 100 nm particles functionalized with carboxyl (C-NPs) or amine (A-NPs) groups. Human SH-SY5Y neuroblastoma cells were exposed to 1-500 μg/mL for 24 or 48 h. Dynamic light scattering revealed aggregation of plain 50 nm NPs in water, while presence of ≥1 % fetal bovine serum improved colloidal stability across all particle types. Zeta potentials in water were approximately -45 mV for plain and C-NPs and -30 mV for A-NPs. In complete medium, all values shifted toward -20 to -13 mV, consistent with protein corona formation. Integrating colloidal stability, surface chemistry, and organelle-level analyses, we established a unified mechanistic framework for PS-NP neurotoxicity. Toxicity endpoints included cell viability, ROS/RNS generation, particle internalization, and morphological and ultrastructural analysis. Plain PS-NPs showed negligible cytotoxicity, whereas C-NPs and especially A-NPs significantly reduced cell viability. A-NPs caused a 21-41 % reduction at 100-500 μg/mL after 24 h, and 29-66 % at 200-500 μg/mL after 48 h (p = 0.0007 vs. C-NPs). ROS/RNS levels were highest with plain 100 nm and A-NPs at ≥200 μg/mL, increasing over time. Transmission electron microscopy revealed size- and surface chemistry-dependent damage, including endoplasmic reticulum dilation, Golgi fragmentation, and mitochondrial abnormalities. Internalization followed the trend A-NPs > C-NPs ≫ plain PS-NPs, mirroring organelle damage, apoptosis, autophagy, and lysosomal disruption. These findings identify surface chemistry, more than particle size, as the primary driver of PS-NP neurotoxicity, highlighting its importance for risk prioritization and regulatory frameworks addressing NP hazards.

Source: Environmental Pollution

DOI: 10.1016/j.envpol.2025.127445