Iron bioavailability from ingested iron oxide nanoparticles

Poster presented at the Fifth Congress of the International BioIron Society (2013) that took place in the University College London (London, United Kingdom) during 14-18th April 2013.
[Introduction] Iron oxide nanoparticles (IONP) have become a powerful platform for several biomedical and environmental applications. The potential of IONP to act as contrast agent, drug and/or gene carrier, biological sensing, or hyperthermia mediator have been proved, however, the assessment of their safety and biocompatibility is mandatory prior to extending theiruse. Thus, the toxicity, biodistribution and excretion after long term exposure of IONP have to be elucidated
[Methods and Materials] The present study reports the iron bioavailability of ingested maghemite (gamma-Fe2O3) IONP. We use chickens as suitable animal model to determine iron availability from maghemite IONP. Thus, we test the effect of a 14 days sustained ingestion of maghemite IONP (sized 6.5 and 12 nm) on plasma haemoglobin, iron excretion and accumulation in spleen and liver.Four experimental diets were fed ad libitum to chickens (12 per experimental group) from 7 to 21 days of age. One of the four groups received a basal iron-deficient diet (with no supplemental iron) while the other three groups were fed with iron-sufficient diets formulated to meet iron requirements by adding a commercial iron source (FeSO4) and two different size (6.5 and 12nm) IONP to the basal diet.
[Results] After 14 days, faeces were collected and blood was sampled after an overnight fast to determine haemoglobin concentration with the cyanmethemoglobin method. Then, birds were euthanized and liver and spleen were collected, weighed and lyophilized for iron and IONP detection and quantification by atomic absorption spectrophotometry and magnetic susceptibility, respectively. Body and organ weight, and feed intake were similar among the four experimental groups. However, chickens fed the iron-deficient diet showed a reduction in plasma haemoglobin and haematocrit values and a lower iron concentration in faeces, liver and spleen than that of chickens fed ironsufficient diets, irrespective of the iron source.
[Conclusion] For all parameters studied, no differences were observed among chickens fed diets supplemented with different iron sources. The latter result reflects a similar iron bioavailability from IONP than that from FeSO4, in agreement with a previous studies reporting no histological accumulation of IONP in tissues of rats fed diets containing iron based nanostructures. The size of IONP does not affect the iron bioavailability. In conclusion, our results indicate that iron from IONP is bioavailable, with no IONP accumulation in the liver or the spleen.