Phenotypic profiling reveals polystyrene nanoplastics elicit sublethal and lethal effects on cellular morphology in rainbow trout gill epithelial cells†

Abstract

Extensive knowledge is available on the impacts of both engineered nanomaterials (ENMs) and microplastics (MPs), yet there remains a critical gap in understanding the impacts of nanoplastics, and the cellular and subcellular effects at sublethal concentrations. This study investigates the impacts of polystyrene nanoplastics (PS NPs) on Oncorhynchus mykiss (rainbow trout) gill epithelial cells, emphasizing the crucial role of surface charge in nano–bio interactions. The current study employs both traditional and non-traditional toxicological techniques presenting an image-based study to examine PS NP–cellular interactions at sublethal and lethal doses. Our findings demonstrated that relative to the uncharged and negatively charged PS NPs, the positively charged PS NPs significantly decreased cell viability at 4 μg mL⁻¹ (EC₅₀: 4.31 μg mL⁻¹). However, at a sublethal concentration of 2 μg mL⁻¹, phenotypic profiling analysis indicates that positively charged PS NPs elicit a significant change to cellular morphology and suggests key interactions with subcellular components. As the impacts measured are novel, further research into the underlying mechanisms will contribute to our understanding of nanoparticle toxicity in vertebrate species guiding both the policy and sustainable design of nanoparticles.