ABSTRACT
A new quercetin nanocrystals self-stabilized Pickering emulsion(QT-NSSPE) was prepared by high-pressure homogenization combined with probe ultrasonic method. The influences of oil fraction, quercetin(QT) concentration, and pH of water phase on the formation of QT-NSSPE were investigated. On this basis, the QT-NSSPE prepared under optimal conditions was evaluated in terms of microstructure, stability, and in vitro release and the droplet size and drug loading were 15.82 μm and 4.87 mg·mL~(-1), respectively. The shell structure formed by quercetin nanocrystals(QT-NC) on the emulsion droplet surface was observed under a scanning electron microscope(SEM). X-ray diffraction(XRD) showed that the crystallinity of adsorbed QT-NC decreased significantly as compared with the raw QT. There were not significant changes of QT-NSSPE properties after 30 days of storage at room temperature. The in vitro release experiment confirmed that QT-NSSPE has a higher accumulative release rate than the raw QT. All these results indicated that QT-NSSPE has a great stability and a satisfactory in vitro release behavior, which is a promising new oral delivery system for QT.
Subject(s)
Emulsions/chemistry , Nanoparticles , Particle Size , Quercetin , Water/chemistryABSTRACT
To investigate the effects of drug and oil properties on the formation and stability of drug nanocrystalline self-stabilizied Pickering emulsions (NSSPE). Three insoluble Chinese medicine components (puerarin, tanshinone ⅡA and ferulic acid) were selected as model drugs, and Capmul C8, Fabrafil M 1944 CS, isopropyl myristate, Pzechwan Lovage Rhizome oil, and olive oil were used as oil phase. NSSPEs were developed by high pressure homogenization method and were evaluated for their appearance, centrifugal stability, droplet size and drug content changes in emulsion layer after storing at room temperature for 14 d. Then the properties of the oil (surface tension and viscosity) and properties of the drugs (surface energy, oil-water partition coefficient, size and Zeta potential of nanocrystalline and drug-water-oil contact angle) on the formation and stability of NSSPE were analyzed. The emulsification property and stability of five samples prepared with ferulic acid nanocrystals and different oils were significantly lower than those of puerarin and tanshinone ⅡA; the particle size of ferulic acid nanocrystals was 3.90 μm, extremely higher than 305 nm of puerarin and 406 nm of tanshinone ⅡA (P<0.05); the zeta potential of ferulic acid nanocrystals was -0.018 0 mV, significantly lower than －29.1 mV of puerarin and -42.6 mV of tanshinone ⅡA (P<0.05). Three samples prepared with isopropyl myristate and different drugs were not emulsions and the viscosity of isopropyl myristate was 4.67 mPa•s, significantly lower than that of the other oils (P<0.01). Puerarin-NSSPEs prepared with Pzechwan Lovage Rhizome oil showed best emulsification property and stability; the contact angle of puerarin in Pzechwan Lovage Rhizome oil-water was 69.7°, close to 90°, significantly higher than other contact angles. NSSPEs made by tanshinone ⅡA-Capmul C8-water, tanshinone ⅡA-Labrafil M 1944 CS-water showed highest stability, with a contact angle of 99.2° and 112° respectively, more close to 90° than other oils. The results indicated that viscosity, size and Zeta potential of nanocrystalline and three-phase contact angle had great influence on the formation and stability of NSSPE; surface tension of oil, surface energy of drug and oil-water partition coefficient may not be related to the construction of NSSPE.
ABSTRACT
Objective: To investigate the feasibility of Pickering emulsion stabilized by puerarin nanocrystalline. Methods: The new puerarin nanocrystalline self-stabilized Pickering emulsion (Pu-NSSPE) has been developed using the high pressure homogenization method. The influences of drug addition sequence, property, and construction of oil phase, drug concentration, oil/water ratio, homogenization pressure, and pH value of water phase on the formation and stability of Pu-NSSPE were investigated to optimize the preparation technology of Pu-NSSPE. Results: The stability and structure of optimized Pu-NSSPE were studied. It was difficult to form stable Pu-NSSPE if puerarin was first added into water during preparation. The three-phase contact angle and pH value of water phase were key factors for the formation and stability of Pu-NSSPE. Pickering emulsion could be stabilized by puerarin nanocrystalline only when three-phase contact angle of puerarin approaches 90° and water phase was alkaline. When the drug concentration was between 1.0-5.0 mg/mL, stable Pu-NSSPE could be formed. The higher oil/water ratio was, the more oil creamed from Pu-NSSPE was. Low homogenization pressure (below 80 MPa) could not form stable Pu-NSSPE. The size of emulsion droplet of optimized Pu-NSSPE was (10.66 ± 4.81) μm, and drug content was 4.28 mg/mL. The appearance, morphology, and size of emulsion droplets, Zeta potential and drug content were not changed significantly after storage for six months at room temperature. The adsorption of puerarin at the surface of oil droplets was observed by fluorescence microscope. Conclusion: Nanocrystalline of puerarin could stabilize Pickering emulsions, which will provide a promising drug delivery system for puerarin.