Preparation of black rice bran anthocyanin liposomes by reverse-phase evaporation combing with pH gradient

Black rice bran anthocyanin liposomes were prepared by reverse phase evaporation combining with p H-gradient technique using the mixture of soybean lecithin and cholesterol as membrane material. On the basis of the single-factor test,the molar ratio between phosphatidylcholine and cholesterol(nSPC/nCH,mol/mol),volume ratio of organic to aqueous phase(VOP/VAP) and the concentration of phosphate buffer were identified as three major factors which affected the encapsulation efficiency. The optimized conditions of anthocyanin liposomes preparation were then obtained by using three factors and three levels of response surface analysis according to central composite(Box-Behnken) experimental design principles. The results showed that the optimum parameters for the preparation of anthocyanin liposomes were found to be nSPC/nCH=3.29/1,VOP/VAP=3.16/1,and the concentration of phosphate buffer was 5.21 mmol/L. The anthocyanin liposome prepared under this optimized condition had the encapsulation efficiency of 54.97%,the average particle size of 234 nm and the Zeta potential of-25.0 m V,which showed that the liposome was stable and suitable for further bio-available study.