The presence of palmitate affected the colloidal stability of ZnO NPs but not the toxicity to Caco-2 cells

Abstract

Nanoparticles (NPs) are finding increasing use in food science, but the toxicity of NPs following oral exposure is not fully known. When present in food and food-related products, food components may interact with NPs and thus influence the toxicity of NPs, but relatively few studies have considered the interactions between food components and ZnO NPs. In this study, the interactions between ZnO NPs with different sizes (20 and 100 nm; uncoated) and palmitate (PA) on the toxicity of NPs to Caco-2 cells were investigated. The presence of PA altered UV-Vis spectra, hydrodynamic size, and zeta potential of ZnO NPs of both sizes, which indicated an interaction between PA and ZnO NPs. Furthermore, the interaction decreased the solubility of ZnO NPs in water and cell culture medium. Exposure to both types of ZnO NPs was associated with significantly increased cytotoxicity, lysosomal damages, and intracellular Zn accumulation but not reactive oxygen species (ROS) or release of interleukin-8 (IL-8) in Caco-2 cells. The presence of 100 μM PA did not significantly affect all of these endpoints, and ANOVA analysis indicated no interaction between concentrations of ZnO NPs and the presence of PA. It is concluded that PA as a saturated fatty acid may influence the colloidal stability of ZnO NPs but did not affect the toxicity of ZnO NPs to Caco-2 cells.