Synthesis, characterization and in vitro release analysis of pluronic F127 copolymer micelles containing quercetin as a hydrophobic drug

The object of the present study is to develop a new controlled drug release system by loading quercetin into pluronic F127 micelles. For the experimental studies, first of all, the critical micelle concentration (CMC) of the pluronic F127 copolymer was found as 4.5% g/mL at 25 degrees C, since the micelle-forming surfactants formed micelles at concentrations equal to or higher than the CMC. Afterward, with thin-film hydration method, three micelle groups with different polymer/quercetin ratios were formed. In this procedure, pluronic F127 polymer dissolved in ethanol at 30-40 degrees C and different amount of quercetin was added to the polymer solution. The polymer-quercetin solutions were evaporated in the evaporator at 40 degrees C for 2 h to obtain a film. The resulting film was hydrated by adding of ultrapure water and the micelle suspensions were obtained after filtration. According to Malvern Zetasizer measurement and transmission electron microscope (TEM) analysis, quercetin loaded micelles were determined to have particle sizes between 40 and 50 nm. It was determined by fourier-transform infrared spectroscopy (FTIR) analysis that quercetin was physically found into pluronic F127 micelles without any chemical reaction. It was determined by X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analyzes that quercetin was present in amorphous form as a solid solution instead of in crystalline form in the micelles. Thermogravimetric analysis (TGA) analysis showed that loading quercetin into the micelles did not affect the thermal stability of the PF127 copolymer. The drug loading amounts for micelles were found between 1.95% and 3.3% (mg/mg) for different micelles groups and there was not much difference in the percentage of encapsulation efficiency values thought to the groups. In vitro release profiles of quercetin-loaded micelles were investigated in pH 7.4 phosphate buffer solution and at 37 degrees C. When the release results were examined in general, it was seen that the release rates of all formulations were almost the same after 168 h. The kinetic parameters of the release results of the micelles in different formulations were calculated according to the Peppas equation and it was determined that the quercetin release in each micelle formulation did not comply with Fick's law, according to the calculated n parameter. Quercetin-loaded polymeric micelles obtained in this study offer advantages due to their easy synthesis methods and slow release profiles and they can used to successfully encapsulation of hydrophobic active ingredients like quercetin.