LDH release in hCMEC/D3 and HDMEC after 48 h exposure to AuNPs. The endothelial cells hCMEC/D3 (A) and HDMEC (B) were exposed to different amounts of gold nanoparticles (50 μM – 1000 μM) for 48 hours. Gold-induced cytotoxicity was measured by the LDH release into the supernatant by an enzymatic assay system. As positive control lysed cells were used and set at 100% (lysis). The spontaneous LDH releases of untreated cells are indicated by the black horizontal line. Each result represents the mean ± standard deviation of three independent experiments, each of these was performed at least in triplicates (ONEway ANOVA with Dunnetts t-test: * P < 0.5; ** P < 0.05; *** P < 0.001).