Electron-Microscopic Investigation of the Distribution of Titanium Dioxide (rutile) Nanoparticles in the Rats' Small Intestine Mucosa, Liver, and Spleen

Background: Titanium dioxide (TiO2) is currently one of the most widely known nanomaterials produced for different purposes. The adverse effects of nano-dispersed TiO2 cause a serious concern about human health problems related to the intake of TiO2 nanoparticles (TiO2 NPs). The investigation of TiO2 NPs' penetration through the gut epithelium into secondary organs and the relevant biological effects has an undoubted importance when assessing the potential risk of using TiO2 NPs. Objective: In the current study, we investigated the effect of rutile TiO2 NPs on tissues of the small intestine, liver, and spleen. For this purpose, we used a physiological model that simulates the single administration of TiO2 NPs directly into the intestinal lumen of an experimental animal. Methods: Suspensions TiO2 NPs were administered via an isolated loop of the small intestine at a single dose of 250 mg/kg of body weight. TiO2 NPs were detected in rats' tissues by transmission electron microscopy. Results: TiO2 NPs were found in tissues of the small intestine mucosa, liver, and spleen. The administration of TiO2 NPs resulted in different changes in the cellular ultrastructures: hyperplasia of the smooth endoplasmic reticulum, an increase in the size of the mitochondria, the emergence of local extensions into the perinuclear space, and the appearance of myelin-like structures. Conclusion: The ultrastructural changes found in the individual cells of the small intestine, liver, and spleen indicated intracellular pathology, induced by the high doses of the TiO2 NPs. The spleen tissue appeared to be the most sensitive to the effect of TiO2 NPs.