Fig. 5. Simoa-based quantification of IL-6 secretion from OVCAR-3 cells. (a) Correlation between IL-6 baseline levels of OVCAR-3 cells measured by Simoa (solid red) or ELISA kit (dotted black) at different cell-seeded density. (b) Simoa-based quantification of IL-6 secretion from OVCAR-3 cells treated with TOP-MSN-PEG, the equivalent amount of TOP alone (positive control), MSN-PEG, and cells only (negative control), with or without ultrasound stimulation (power density: 75 W cm²; stimulation time: 30 s). IL-6 concentrations were measured by IL-6 Simoa assay. Data are means ± SD of two independent experiments (*P < 0.05; **P < 0.01; ***P < 0.001).