Toxicity of nanofibers on zebrafish embryogenesis – Impact of materials properties on inflammatory responses

Textile microfibers are the most common form of microplastic pollution and among the most dangerous to wildlife across multiple biomes. Besides toxicological challenges arising from their shapes, the morphology of fibrous materials make them excellent adsorbents and transportation media for harmful chemical pollutants and support both uptake and bioaccumulation across living organisms. The fragmentation of microfibers used in the textile industry is shown to lead to the formation of a broad range of sub-micron and nanofibers, with greater surface to volume ratio and much finer diameters, whose toxicity and environmental impact are not yet understood. Here, the impact of nanofibers on zebrafish embryos is studied to reveal risks associated with nanofiber pollution during early developmental stages. Exposure of embryos to nanofibers at a similar concentration to what has been observed in polluted water streams was found to dramatically increase apoptosis, neutrophils, and cytokine production that the chorion was unable to protect against. Furthermore, disturbed vascular basement membrane assembly in exposed embryos was detected leading to an expanded dorsal aorta diameter. These results obtained with model nanofibers demonstrate the risks of fragmented microplastics and the impact of surface properties on uptake and response by living organisms.