Stability optimization of puerarin nanocrystalline self-stabilizied Pickering emulsion by response surface methodology

A new Pickering emulsion, puerarin nanocrystalline self-stabilized Pickering emulsion (Pu-NSSPE) was developed. Box-Behnken design was used for optimizing the preparation formulation of Pu-NSSPE to improve its stability, and the effects of concentration of puerarin, volume ratio of water to oil, and pH value of water phase on the stratification index of emulsion, droplet size and drug concentration in emulsion were investigated. Results showed that the optimized Pu-NSSPE could be prepared with the concentration of puerarin of 0.5%, the volume ratio of water to oil of 9-1 and the pH of water of 9. The size of emulsion droplet of optimized Pu-NSSPE was (12.70 ±1.17) μm and the drug content was (4.49 ±0.21) g · L ^-1 . The above indexes had no significant changes within the storage of 6 months at room temperature, indicating good stability. Microstructure characterizations by scanning electron micrograph, confocal laser scanning microscope and fluorescence microscope showed that the optimized Pu-NSSPE had a stable core-shell structure of emulsion droplet formed by the adsorption of puerarin nanocrystallines at the surface of oil droplets, which may be the microstructure reason for the long stability of Pu-NSSPE.