Nanocarriers for antioxidant resveratrol: formulation approach, vesicle self-assembly and stability evaluation

In this work we studied various nanoformulations of resveratrol in phospholipid vesicles. Conventional phophatidylcholine liposomes were prepared and characterized in parallel with PEVs (Penetration Enhancer-containing Vesicles) obtained by adding one of eight selected amphiphilic penetration enhancers (PEs; 0.2% w/v; HLB range 1-16) to the composition. All vesicles were around 100 nm, negatively charged (∼-30 mV) and able to incorporate resveratrol in good yields (>74%). The structure and the lamellar self-organization of the vesicles were investigated by Transmission Electron Microscopy (TEM) and Small and Wide Angle X-ray Scattering (SWAXS). These analyses showed that the lamellarity of the vesicles depended on the formulation composition. This work also addressed the stability of our colloidal dispersions, which was measured by means of the analytical centrifuge LUMiSizer(®): this procedure disclosed the absence of any demixing phenomena and estimated a 3- to 6-month shelf-life. Moreover, the antioxidant activity of resveratrol was determined by assessing its ability to scavenge free radicals (DPPH assay), and showed that it was not affected by the vesicular formulation.