TNF-α levels in the supernatants (upper chamber, lower chamber) were measured by ELISA. TNF-α release in cells exposed to LPS, 1 μm, and 0.078 μm polystyrene particles, TiO, and gold NP. Values are means ± SD of 3 experiments. * indicates a statistical difference to the levels in the supernatants in the control of the upper chamber, indicates a statistical difference to the levels in the supernatants in the control of the lower chamber.