In evaluating the entrapment efficiency (EE), PALNs prepared were stored in − 80°C freezer for 24 h. Then PALNs were thawed and isolated by centrifugation at 48,000×g at 4°C for 20 min. The supernatants consisted of the free drug were:2 EE%=Mtotal–Mfree/Mtotal100%where EE was the entrapment efficiency, and Mtotal and Mfree were a total mass of ACV added and free ACV in supernatant respectively.