Preparation, characterization and properties of liposome-loaded polycaprolactone microspheres as a drug delivery system

We reported the preparation and properties of liposome-loaded polycaprolactone microspheres (LPMs) as a drug delivery system for controlling the release of flurbiprofen. LPMs were fabricated using double emulsion solvent extraction/evaporation method and characterized by scanning electron microscopy, Fourier transform infrared spectrum, X-ray diffraction, differential scanning calorimeter and UV–vis spectrum. The results suggest that LPMs have uniform sizes with pores on the external surface. Liposomes are intactly encapsulated in LPMs, which causes slight change of polycaprolactone from semi-crystalline to less-ordered amorphous. The concentrations of polycaprolactone and polyvinyl alcohol (PVA) and the amount of liposomes can affect the diameter, surface morphology and encapsulation efficiency of LPMs. The diameter of LPMs increases from 80 to 200 μm and the encapsulation efficiency of flurbiprofen in LPMs increases from 36.92% to 48.42% when the concentration of polycaprolactone increases from 0.15 to 0.6 g/mL. However, the larger amount of liposomes promotes the aggregation between emulsion droplets and causes more pores on the surface of LPMs, which leads to lower drug encapsulation efficiency. The presence of PVA stabilizes the emulsion droplets against coalescence. With the increase of PVA concentration, the diameter of LPMs decreases and the amount of flurbiprofen encapsulated in LPMs increases. In vitro release studies suggest the structure and morphology of LPMs have close relationship with drug release kinetics. The smaller LPMs with more porous surface have faster cumulative release rate.