Fig. 4. Analysis of ROS induction in hepatic cell lines upon co-treatment with IONPs and fatty acids. Alexander (a) or HepG2 (b) cells were co-treated with IONPs (50 μg ml⁻¹) and either OA or PA (20 μM for Alexander and 200 μM for HepG2 cells) in accordance with scheme Fig. 1b. Treated cells were stained with a ROS/Superoxide Detection Assay Kit (Abcam, Cambridge, United Kingdom) and imaged by confocal microscopy. ImageJ software (NIH) was used for image processing and quantification. (**) P < 0.01 and (***) P < 0.001 denote significant differences. Positive control 100 μM H₂O₂ for 30 min was used.