Preparation of hollow PCL microspheres by o/w single emulsion-solvent evaporation method in the presence of graphene nanopowders

Poly-epsilon-caprolactone (PCL) microspheres containing graphene nanopowders were prepared by oil-in-water (o/w) emulsion solvent-evaporation technique. For the emulsification study, an oil phase (PCL solution in dichloromethane or chloroform) and a water phase (3 wt% aqueous polyvinyl alcohol solution) was utilized. Effect of solvent type, stirring speed, and graphene addition on the structural and morphological properties of the prepared microspheres was investigated. Results showed that stable emulsification of oil in water (o/w) was achieved with a 5 wt% PCL. A decrease in particle size was observed for the PCL microspheres prepared by chloroform (19.02 +/- 6.41 mu m) compared to the microspheres obtained by dichloromethane (59.81 +/- 23 mu m) under the same conditions. Results also revealed that the addition of graphene changed the morphology and particle size of the microspheres significantly. Hollow PCL microspheres were obtained in the presence of graphene nanopowders when chloroform was utilized as the solvent. Drug release experiments indicated that hollow PCL-graphene composite microspheres have improved release behavior compared to bare solid PCL microspheres. The particles prepared in the study have the potential to be used in drug delivery and tissue engineering applications.