In vivo study of chelating agent-modified nano zero-valent iron: Biodistribution and toxicity in mice

•nZVIs were mainly distributed in the livers and spleens of mice.•Liver showed inflammation at 14th d gavage, while the other organs did not.•nZVIs did not affect the mice body weight or on the weight of the organs.•nZVIs caused liver inflammation in mice, but were not significantly toxic to mice.•Chelators have no notable effects on the distribution and toxicity of nZVI in mice. In this study, the distribution and toxicity of nanoscale zero valent iron (nZVI) and nZVIs coated with citric acid and sodium tripolyphosphate (CA-nZVI and STPP-nZVI) in mice were investigated. nZVIs were primarily found in the livers and spleens, followed by the lungs, hearts, and kidneys. Histologic analysis revealed no significant histopathologic abnormalities or lesions in all organs except the liver at 14th d gavage. nZVIs did not have a noticeable impact on the body weight of the mice or the weight of their organs. Compared with the control group, there were no significant changes in hematology indexes in the nZVIs groups. However, the nZVIs groups exhibited varying levels of elevation in alanine aminotransferase, aspartate aminotransferase, and creatinine, suggesting liver and kidney inflammation in mice. The up-regulation of Nuclear Factor erythroid 2-Related Factor 2 and Heme oxygenase 1 in the nZVIs groups may be a response to nZVIs-induced oxidative stress. Immunohistochemical analysis confirmed the inflammatory response induced by the three nZVI groups. Chelating agents did not have a significant impact on the distribution or toxicity of nZVIs in mice. This study contributes to a comprehensive and detailed insight into nZVI toxicity in the environmental field. [Display omitted]