The synthesis of folate-targeted chitosan nanoparticles for the co-delivery of 5-FU and methotrexate: comprehensive studies on drug release, cellular uptake, and cytotoxicity

The synthesis of folic acid (FA)-conjugated chitosan (CS) nanoparticles (NPs) was investigated for the co-delivery of 5-Fluorouracil (5-FU) and Methotrexate (MTX) to target colon cancer cells. NPs were characterized using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscope (SEM), and other methods. The optimized FA-CS-5-FU-MTX-NPs had a particle size of 408.1 ± 7.3 nm, a zeta potential of 13 ± 2.7 mV, and exhibited smooth, spherical morphology. The percentage (%) of drug content (DC) and entrapment efficiency (EE) were 82.9 ± 2.5% and 63.9 ± 2.3% for 5-FU, and 83.3 ± 2.5% and 70.7 ± 0.8% for MTX, respectively. It shows minimal release at a pH of 1.2 and maximum release at a pH of 7.4. FA-conjugated NPs reaches up to 85.55% for MTX at a pH of 7.4 within 24 h, indicating pH-responsive behavior. FA-CS-5FU-MTX-NPs increased 5-FU Tmax from 1 to 12 h, T1/2 from 0.23 to 2.34 h, and area under the curve (AUC) from 5.41 to 25.08 µg·h/mL; MTX Tmax rose from 1.5 to 15.91 h, T1/2 from 0.56 to 3.40 h, and AUC from 10.72 to 39.51 µg·h/mL. In the cytotoxicity study, FA-CS-5-FU-MTX-NPs induced the highest cell death (∼65%). This indicates the enhanced anticancer efficacy of NPs’ formulations, especially with FA targeting.