Title : Active loading of resveratrol in transferrin-functionalised liposomes using a pH gradient technique
Resveratrol, a polyphenol, found in grapes and red wine, has been reported to have many potential therapeutic properties. However, resveratrol demonstrates poor water solubility and short biological half-life, and lacks therapeutic efficacy due to inadequate concentration at the site of action. Resveratrol is a lipophilic compound and could be accommodated, in small quantities, in the lipophilic lipid bilayer of liposomes. The aim of the current study was to substantially improve resveratrol incorporation within liposomes, thereby improving the potential for more effective liposomal delivery of the polyphenol. Liposomes were prepared using the thin film hydration method and active loading was carried out using a pH gradient as a driving force for resveratrol incorporation. Liposomal particle size was analysed by photon correlation spectroscopy and morphology was assessed by transmission electron microscopy (TEM). Small-angle x-ray diffraction (SAXS) analysis was carried out to estimate the thickness of the lipid bilayer. The release profile of resveratrol was also analysed. The level of resveratrol incorporated into liposomes using the active loading technique was significantly higher than that observed with the passive loading approach. The resveratrol encapsulation efficiency under passive loading conditions was 0.6 %, increasing significantly to 33 % with active loading. The liposomes produced were homogeneous spherical particles, with diameters of between 80 – 100 nm. The thickness of the lipid bilayer as measured using SAXS was 8.1 ± 0.3 nm. The release profile of resveratrol was biphasic, which is typical of a sustained release formulation. Active loading using a pH gradient is an extremely promising approach for successfully loading high concentrations of resveratrol into liposomes, and could be applicable for increasing the encapsulation efficiency of other lipophilic compounds.
•A new technique has been introduced to load a lipophilic drug into liposomes.
•This technique will help other researchers to load any lipophilic drug into liposomes.
•The technique is simple and fast with sufficiently high loading capacity could be achieved.