Cytotoxicity evaluation of silica nanoparticles using fish cell lines

Nanoparticles (NPs) have extensive industrial, biotechnological, and biomedical/pharmaceutical applications, leading to concerns over health risks to humans and biota. Among various types of nanoparticles, silica nanoparticles (SiO₂ NPs) have become popular as nanostructuring, drug delivery, and optical imaging agents. SiO₂ NPs are highly stable and could bioaccumulate in the environment. Although toxicity studies of SiO₂ NPs to human and mammalian cells have been reported, their effects on aquatic biota, especially fish, have not been significantly studied. Twelve adherent fish cell lines derived from six species (rainbow trout, fathead minnow, zebrafish, goldfish, haddock, and American eel) were used to comparatively evaluate viability of cells by measuring metabolic impairment using Alamar Blue. Toxicity of SiO₂ NPs appeared to be size-, time-, temperature-, and dose-dependent as well as tissue-specific. However, dosages greater than 100 μg/mL were needed to achieve 24 h EC₅₀ values (effective concentrations needed to reduce cell viability by 50%). Smaller SiO₂ NPs (16 nm) were relatively more toxic than larger sized ones (24 and 44 nm) and external lining epithelial tissue (skin, gills)-derived cells were more sensitive than cells derived from internal tissues (liver, brain, intestine, gonads) or embryos. Higher EC₅₀ values were achieved when toxicity assessment was performed at higher incubation temperatures. These findings are in overall agreement with similar human and mouse cell studies reported to date. Thus, fish cell lines could be valuable for screening emerging contaminants in aquatic environments including NPs through rapid high-throughput cytotoxicity bioassays.