Fig. 5. Oxidative stress as assessed by the measurement of intracellular GSH (A) or ROS (B). HUVECs were exposed to 64 μg mL⁻¹ XFM19 (pristine MWCNT) and XFM21 (carboxylated MWCNT) with or without pre-incubation with BSA in serum free medium for 6 h, followed by the measurement of intracellular GSH or ROS to indicate oxidative stress. *: p < 0.05, compared with control; #: p < 0.01, compared between the groups exposed to MWCNTs with or without pre-incubation with BSA.