In vitro cytotoxicity assay

MCF-7 and HeLa cells were seeded at a density of 1×10⁴ cells per well in a 96-well plate and allowed to adhere for 24 h. The medium was then replaced with fresh medium containing different concentrations of paclitaxel, PTX-PLGA NPs or PTX-FPLGA NPs (0.01 and 0.1 μM paclitaxel). Blank nanoparticles of the same PLGA content were used as controls. After 48 h of incubation, 20 μL of 5 mg/mL MTT solution was added to each well and cultured for 4 h. Next, the MTT medium was discarded and dimethylsulfoxide (100 μL/well) was added. The absorbance of the DMSO solution was measured at a wavelength of 490 nm using an ELISA plate reader. The cell inhibition rates after treatment with the parent drug and nanoparticles were assayed according to the MTT method.