Microparticles Based on Polycaprolactone, Xanthan Gum, and Chrysophanol: Optimization, Characterization, Bioactivities, Drug Release Performance, and Release Mechanism Insight

In recent years, emulsion-derived microparticles have been applied widely in drug delivery and controlled drug release, especially for those with low solubility in water. Optimizing the ratio of components in a drug-loaded emulsion system is crucial, as it dictates the stability and drug release control of the final product. In this paper, the microparticle system obtained by the emulsion method chosen to study was prepared from poly(caprolactone) (PCL), xanthan gum (XG), and Tween 80 for loading chrysophanol (CHR), as a poorly water-soluble model drug. The ratio of components was surveyed to find the optimal composition for the system stability and droplet size. The optimized emulsion system was loaded with varied drug concentrations and then sedimented, washed, and dried to form solid PCL/XG/CHR (PXC) microparticles. The solid particles were characterized by field emission scanning electron microscopy, ζ-potential and size distribution, infrared spectroscopy, differential scanning calorimetry, and X-ray diffraction analysis. Additionally, physicochemical and pharmacological properties of these emulsion-derived microparticles have also been studied. The CHR structure was changed from crystalline to amorphous when it was loaded in these microparticles. The CHR release process from these particles is also sensitive to pH and can be controlled by the interaction of the drug with polymer matrices. The CHR release mechanism from PXC particles in simulated body fluids is also proposed. Emulsion-derived microparticles containing CHR (PXC1) with high stability, good drug release profile, nontoxicity, and biologically activity have the potential for biomedicine applications.