3.6. Cell Culture Assays

For cytotoxicity tests, MCF-7 and MDA-MB-231 cell lines were used and cultured according to the producer’s protocol. Briefly, the cells were grown in DMEM medium supplemented with 10% fetal bovine serum, 100 μg/mL streptomycin and 100 IU/mL penicillin. For this study, 5 × 10³ cells/well were cultivated in 96-well tissue culture plates at a temperature of 37 °C, in a humidified atmosphere containing 5% CO₂. The magnetic composites nanoparticles (both types) were suspended in the above-specified medium at different concentrations (100, 75 and 50 μg/mL) and applied to the culture wells in 200 µL volume. The cells were incubated for 48 h in the same conditions and standard MTT assay was performed on the samples, using Tecan Sunrise Plate Reader, at 570 nm. The results are expressed as a mean ± standard deviation (SD) (n = 3).