2.8. MTT Assay

The cytotoxicity of free 5-FU (0.01 µg/mL), MF-fabricated NPs based on PLGA with concentrations of 0.1% and 0.2% (w/v) containing the drug and control (the cells feeding with culture medium), was determined by MTT assay. To assess the relative cell viability of the samples, the cell lines were seeded on into a 96-well culture plate with a density of 5×10³ cells/well. After 24 h, 48 h and 72 h of incubation, the amounts of formazan representing the alive cells were measured using an ELISA reader (EL-312, BioTek Instruments Inc., Winooski, VT, USA) at 540 nm absorbance. Afterward, the relative cell viability was obtained by dividing the optical density (OD) of each sample (recording changes in absorbance at 540 nm and a reference wavelength of 620 nm) by OD of control based on Equation (3) [37]: