Fig. 1.

Effects of SiO₂-n and SiO₂-p NPs in vitro. a-d Dose dependent effects of SiO₂-n and SiO₂-p (22.5, 45, 90, and 180 μg·mL^− 1) on NR8383 cells, taken from [54]. Release of a lactate dehydrogenase (LDH), b glucuronidase (Glu), c H₂O₂, and d tumor necrosis factor α (TNF-α). LDH and Glu activities were measured relative to positive control (Triton X-100-lysed cells) after 16 h. The H₂O₂ concentration was measured in μmol·L^− 1 after 90 min, and bioactive TNF-α was measured after 16 h as lysis of TNF-α responsive L-929 cells. All columns represent mean values ± standard deviation of 3 independent experiments. Untreated cells served as controls (n = 3) whose mean values are indicated by dashed lines. Significance was tested by two-way ANOVA and post-hoc Dunnett’s multiple comparison test (*: p ≤ 0.05, **: p ≤ 0.01, ***: p ≤ 0.001)