In an article published on April 6, 2016 in the peer-reviewed journal Food Additives & Contaminants: Part A, Susana Addo Ntim and colleagues from the Center for Food Safety and Applied Nutrition of the U.S. Food and Drug Administration (FDA) evaluate the influence of aqueous food simulants on the size and dissolution of silver nanoparticles (AgNPs) under conditions used to test the migration from nano-enabled food contact materials (FCMs).
Polyvinylpyrollidone-coated spherical AgNPs with a nominal diameter of 60 nm were spiked into three food simulants (water, 10% ethanol, and 3% acetic acid) and incubated for 4 hours at 100°C. Size and dissolution of AgNPs before and after the incubation were evaluated using several state-of-the-art techniques for nanoparticle characterization (transmission electron microscopy, asymmetric field flow fractionation, single particle inductively coupled plasma mass spectrometry (sp-ICP-MS), and ultrafiltration followed by ICP-MS).
All techniques collectively demonstrated that size and dissolution of AgNPs remained largely unaffected after incubation in water or 10% ethanol. In contrast, incubation in 3% acetic acid resulted in the disappearance of most initially present AgNPs, as around 90% of nanoparticulate silver dissolved in this food simulant. The remaining nanoparticles had 70% smaller diameter, likely due to silver oxidation and dissolution from their surface. Time-resolved analysis demonstrated that most AgNPs dissolved within the first hour of incubation.
The results of this study may provide a (partial) explanation for conflicting reports on the occurrence or absence of AgNP migration from FCMs. Clearly, nanoparticle migration studies should take into account the potential influences of food simulants or foods, and analyze not only nanoparticulate, but also the ionic species that could be generated by the investigated nanomaterial.
Addo Ntim, S. et al. (2016). “Influence of aqueous food simulants on potential nanoparticle detection in migration studies involving nanoenabled food contact substances.” Food Additives & Contaminants: Part A (published online April 22, 2016).