Characteristics of niosomes prepared by supercritical carbon dioxide (scCO 2) fluid

Abstract

Characteristics of niosomes prepared by a novel supercritical carbon dioxide fluid (scCO 2) technique have been investigated. Niosomes were composed of Tween61/cholesterol at 1:0, 3:1, 1:1, 1:3 and 0:1 molar ratios and entrapped with d-(+)-glucose by the scCO 2 method without and with ethanol at 5, 10 and 15 % (w/w) as a co-solvent, and the conventional chloroform film method with sonication. Tween61/cholesterol at 1:1 molar ratio niosomes prepared by all methods exhibited the best physical stability. Niosomes by the scCO 2 method with 10 % (w/w) ethanol gave higher trapping efficiency (12.22 ± 0.26%) than those by the conventional chloroform film method with sonication (10.85 ± 0.24%) and the scCO 2 method without ethanol (8.40 ± 1.60%). Niosomes by the scCO 2 method with and without ethanol were large unilamellar structure under TEM with the average sizes of 271.9 ± 159.6 and 202.5 ± 136.7 nm, respectively, whereas those by the conventional chloroform film method with sonication were multilamellar and unilamellar structure with the average size of 58.4 ± 74.6 nm. However, the dispersibility of niosomes by the conventional chloroform film method with sonication was better than that by the scCO 2 either with or without ethanol, because of smaller particle size. This present study has demonstrated the trapping efficiency enhancement of water-soluble compounds in niosomes by the scCO 2 method with 10 % (w/w) of ethanol.