3.6. In Vitro Drug Release Kinetics

The PLGA-PEI-EPI-PTX NPs were dispersed in phosphate buffer (pH 5 and 7.4) at a final concentration of 1 mg/mL and kept in a shaker at 37 °C. The samples were drawn out at different time intervals i.e., after 2, 4, 6, 8, 10, 12, 24, 48 and 72 h. The supernatant of the samples were collected after centrifugation at 17,000× g for 15 min. The volume was compensated with an equal volume of fresh buffer medium. The supernatant contains the released PTX and EPI which was further measured through UV-vis spectrophotometry. The absorbance was recorded at 227 nm and 485 nm wavelength, and cumulative drug release profile was analysed as per the obtained absorbance. Additionally, to enumerate the release mechanism and kinetics from the nanoparticles, the results were fitted in various kinetic models, to get the best fit.