2.6. Cytotoxicity assays

MTT assays were used to probe cellular viability. Cells were seeded at a density of 5000 cells well⁻¹ (100 μL total volume well⁻¹) in 96-well assay plates. After 24 h incubation, the as-prepared AuNCs, at the indicated concentrations, were added for further incubation of 24 h. To determine toxicity, 10 μL of MTT solution was added to each well of the microtiter plate and the plate was incubated in the CO₂ incubator for an additional 4 h. Then the cells were lysed by the addition of 100 μL of DMSO. Absorbance values of formazan were determined with microplate reader at 490 nm (corrected for background absorbance at 630 nm). Three replicates were done for each treatment group.