Nanoparticles were prepared using an oil-in-water emulsion solvent evaporation method together with an ultrasonification technique (Byun, Hwang, et al., 2011). In this procedure, 300 mg of PCL was dissolved in 10 mL of methylene chloride containing 10 mg of α-tocopherol. A 2% PVA (w/v) solution was prepared in PBS solution. The PCL solution was added to 40 mL of the PVA solution. The total mixture was then placed in an ice bath and emulsified using a Branson Digital Sonifier (model 250, Connecticut, USA) with 55 W of energy output for 3 min to obtain an oil-in-water emulsion. An additional 40 mL of the PVA solution was added to the emulsion. The final solution was stirred for 12 h on a magnetic stir plate to allow the evaporation of methylene chloride and to allow the formation of the nanoparticles. The suspension was then centrifuged at 4880 × g for 20 min. The pellet was resuspended in distilled water and centrifuged three more times at 1220 × g for 20 min each. The resulting nanoparticles were collected and frozen at −80 °C for at least 2 h and subsequently freeze dried for 2 days. The freeze dried nanoparticles were stored at 4 °C.