Effects of ingested nanomaterials on tissue distribution of co-ingested zinc and iron in normal and zinc-deficient mice

Cellulose nanofibers (CNF) reduced serum triglyceride levels in rats when co-administered with heavy cream by gavage. Do CNF and other nanomaterials (NMs) alter the tissue distribution and retention of co-administered metal ions? We evaluated whether 5 different NMs affected tissue distribution of co-ingested 65Zn++ and 59Fe+++ in zinc-replete versus zinc-deficient mice. Male C57BL/6J mice were fed either zinc-replete or zinc-deficient diets for 3 weeks, followed by gavage with NM suspensions in water containing both 65ZnCl2 and 59FeCl3. Urine and feces were measured for 48 h post-gavage. Mice were euthanized and samples of 22 tissues were collected and analyzed for 65Zn and 59Fe in a gamma counter. Our data show that zinc deficiency alters the tissue distribution of 65Zn but not of 59Fe, indicating that zinc and iron homeostasis are regulated by distinct mechanisms. Among the tested NMs, soluble starch-coated chitosan nanoparticles, cellulose nanocrystals, and TiO2 reduced Zn and Fe tissue retention in zinc-deficient but not in zinc-replete animals.