Aluminum and aluminum oxide nanomaterials uptake after oral exposure - a comparative study

The knowledge about a potential in vivo uptake and subsequent toxicological effects of aluminum (Al), especially in the nanoparticulate form, is still limited. This paper focuses on a three day oral gavage study with three different Al species in Sprague Dawley rats. The Al amount was investigated in major organs in order to determine the oral bioavailability and distribution. Al-containing nanoparticles (NMs composed of Al⁰ and aluminum oxide (Al₂O₃)) were administered at three different concentrations and soluble aluminum chloride (AlCl₃·6H₂O) was used as a reference control at one concentration. A microwave assisted acid digestion approach followed by inductively coupled plasma mass spectrometry (ICP-MS) analysis was developed to analyse the Al burden of individual organs. Special attention was paid on how the sample matrix affected the calibration procedure. After 3 days exposure, AlCl₃·6H₂O treated animals showed high Al levels in liver and intestine, while upon treatment with Al⁰ NMs significant amounts of Al were detected only in the latter. In contrast, following Al₂O₃ NMs treatment, Al was detected in all investigated organs with particular high concentrations in the spleen. A rapid absorption and systemic distribution of all three Al forms tested were found after 3-day oral exposure. The identified differences between Al⁰ and Al₂O₃ NMs point out that both, particle shape and surface composition could be key factors for Al biodistribution and accumulation.