CEL NE was prepared by an ultrasonic emulsification method. Briefly, celastrol (1 mg) was dissolved in ethanol (10 μL) and then mixed with sesame oil (25 mg) and soybean lecithin (25 mg). Pluronic F68 solution (1 mL, 100 mg/mL) was added dropwise into the above drug mixture under stirring for 5 min at room temperature, then ultrasonicated on an ice bath for 5 min, and finally dialyzed against 5% glucose for 3 h to adjust the osmotic pressure and remove the ethanol.
The size and zeta potential of the CEL NE were determined by the Malvern ZetaSizer Nano series (Westborough, MA). Transmission electron microscopy (TEM, JEOL 1230) images were acquired after CEL NE nanoparticles were negatively stained with 2% phosphotungstic acid. The encapsulation efficiency (EE) of CEL NE was calculated as the percent of the amount of CEL loaded in the CEL NE analyzed using the HPLC system (Shimadzu LC-20AT, Kyoto, Japan) over the original feeding amount. Thermo Scientific C18 column (100 mm × 4.6 mm, 2.6 μm, Thermo Fisher Scientific, Waltham, MA USA) with 44:44/12 acetonitrile/methanol/water (1% formic acid) as the mobile phase (0.2 mL/min) at room temperature was used. Pure CEL appeared at 9.2 min was used as a standard.
The size and zeta potential of the CEL NE were determined by the Malvern ZetaSizer Nano series (Westborough, MA). Transmission electron microscopy (TEM, JEOL 1230) images were acquired after CEL NE nanoparticles were negatively stained with 2% phosphotungstic acid. The encapsulation efficiency (EE) of CEL NE was calculated as the percent of the amount of CEL loaded in the CEL NE analyzed using the HPLC system (Shimadzu LC-20AT, Kyoto, Japan) over the original feeding amount. Thermo Scientific C18 column (100 mm × 4.6 mm, 2.6 μm, Thermo Fisher Scientific, Waltham, MA USA) with 44:44/12 acetonitrile/methanol/water (1% formic acid) as the mobile phase (0.2 mL/min) at room temperature was used. Pure CEL appeared at 9.2 min was used as a standard.