Effects of starch-coating of magnetite nanoparticles on cellular uptake, toxicity and gene expression profiles in adult zebrafish

Highlights: • Starch coating affect biological responses to Fe₃O₄ nanoparticles (NPs). • Responses of zebrafish to bare and coated NPs are analyzed by RNA-seq. • Toxicity of Fe₃O₄ NPs is dependent on tissue and particle surface chemistry. • Bare NPs cause more cytotoxicity to gill, and coated NPs trigger more harm to liver. • Both bare and starched NPs could induce inflammation and oxidative stress. Engineered magnetite nanoparticles (Fe₃O₄ NPs) have been used in many fields. To prevent particle agglomeration, stabilizers or coatings are often required. While such coatings have been shown to enhance performances, the environmental impact or toxicity of stabilized or coated Fe₃O₄ NPs remain poorly understood. In an effort to understand the impacts of such coatings on the toxicity of Fe₃O₄ NPs, we used the transcriptome sequencing (RNA-seq) technique to characterize the gill and liver transcriptomes from adult zebrafish when exposed to bare and starch-stabilized Fe₃O₄ NPs for 7 days, demonstrating remarkable differences in gene expression profiles, also known as differentially expressed genes (DEGs) profiles, in both tissues. Bare Fe₃O₄ NPs exerted greater toxicity than starch-coated Fe₃O₄ NPs in gill; in contrast, starch-Fe₃O₄ NPs triggered more severe damage on liver, though both bare and stabilized NPs appeared to share similar regulatory mechanisms. Quantitative real-time polymerase chain reactions using six genes each for the two tissues verified the RNA-seq results. The surface coatings play an important role in determining the nanoparticle toxicity, which in turn modulate cell uptake and biological responses, consequently impacting the potential safety and efficacy of nanomaterials.