Exposure to epoxy-modified nanoplastics in the range of µg/L causes dysregulated intestinal permeability, reproductive capacity, and mitochondrial homeostasis by affecting antioxidant system in Caenorhabditis elegans.

ABSTRACT

Although surface chemically modified nanopolystyrene (PS) has been reported to have potential toxicity toward organisms, the impact of epoxy modification on the toxicity of PS remains largely unknown. In this study, we first investigated the prolonged exposure effects of epoxy-modified PS (PS-C2H3O) in the range of µg/L on Caenorhabditis elegans (C. elegans) including general toxicity, target organ toxicity, and organelle toxicity. Our data revealed that C. elegans exposed to PS-C2H3O led to the alterations in increased lethality (≥ 1000 µg/L), shortened body length (≥ 100 µg/L), and decreased locomotion capacity (≥ 1 µg/L). In addition, toxicity analysis on target organs and organelles indicated that exposure to PS-C2H3O enhanced intestinal permeability (≥ 100 µg/L) by inhibiting the transcriptional levels of acs-22 (encoding fatty acid transport protein) (≥ 100 µg/L) and hmp-2 (encoding α-catenin) (≥ 1000 µg/L), reduced reproductive capacity (≥ 10 µg/L), and dysregulated mitochondrial homeostasis (≥ 1 µg/L). Moreover, the activation of antioxidant enzyme system could help nematodes against the toxicity caused by PS-C2H3O exposure (≥ 10 µg/L). Furthermore, we also compared the toxicity of PS-C2H3O with other chemically modified derivatives of PS, and the toxicity order was PS-NH2 > PS-SOOOH > PS-C2H3O > PS-COOH > PS > PS-PEG. Our study highlights the potential environmental impact of PS and its derivatives on organisms and suggests that the toxicity of nanoplastics may be charge-dependent.