IAP activity after four hour exposure to zinc oxide nanoparticles in DMEM and digest. One way ANOVA reveals no significant difference between treatments. Mean, +/−SEM, and Tukey groups are shown, n=18. Bars that do not share any letters are significantly different according to a one-way ANOVA with Tukey’s post test (p < 0.05). Low, medium and high refer to the dose of ZnO nanoparticles, where low = 9.7 × 10−6 mg/mL, medium = 9.7 × 10−4 mg/mL, and high = 9.7 × 10−2 mg/mL. Digest refers to ZnO nanoparticles that have been subjected to a simulated gastric and intestinal digestion.