Studies on crystallinity state of puerarin loaded solid lipid nanoparticles prepared by double emulsion method

In this work, solid lipid nanoparticles (SLN) have been prepared from water-in-oil-in-water double emulsion, using monocaprate as solid lipid, sorbitan monooleate (Span 80) and polyoxyethylene sorbitan monolaurate (Tween 20) as emulsifier, and puerarin as target drug. The morphology of SLN with drug loaded or not was investigated by the transmission electron microscope (TEM). The crystal order and structure of particles were studied by differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD), respectively. The results indicate that the diameters of SLN with puerarin inside are larger than those without drugs. The analysis of WAXD and DSC shows that the state of crystallinity SLN prepared by double emulsion method was worse than that of SLN prepared by microemulsion. And also the drug-loaded SLN presents a less ordered crystallinity than the drug-free SLN. But both the drug-free and drug-loaded SLN exist in an amorphous state. The reasons of the phenomenon have been discussed.