Solubility of ZnO Nanoparticles in Food Media: An Analysis Using a Novel Semiclosed Dynamic System

Food media can affect the solubility of zinc oxide nanoparticles (ZnO NPs). Moreover, when a single digestive fluid and a three-step digestion system were applied to investigate the fate of ZnO NPs, several contradictory results were obtained. Here, we manipulated a novel semiclosed in vitro dynamic digestion system to investigate the difference in the released ionic zinc (Zn²⁺) content in three types of artificial fluids in the presence of different food media. The results show that there was a significant difference in the released Zn²⁺ content between the three different types of digestion systems in the presence of the same food media. In addition, the released Zn²⁺ content was significantly different when different types of food media were applied to the same digestion system. These results demonstrate that the different levels of released Zn²⁺ content can be ascribed to the difference in digestion systems and food media.