A novel method of vesicle preparation by simple dilution of bicelle solution

Abstract

We prepared phospholipid vesicles in continuous dilution from small phospholipid bilayer bicelles. As vesicles are useful as delivery carriers, it is necessary to develop a method of continuous encapsulation. Bicelles are composed of long-chain 1,2-dimyristoyl-sn-glycero-3-phosphocholine in bilayers and short-chain 1,2-dihexanoyl-sn-glycero-3-phosphocholine as a detergent. Bicelles were diluted in a batch system and a flow system and their membrane properties were compared; sizes were analyzed by dynamic light scattering and membrane properties by fluorescence spectroscopy. In the flow system, the initial bicelles (10−20 nm) coalesced by dilution and hydration of the detergent into large vesicles (>30 nm). Uptake of methylene blue solution revealed the internal aqueous phase. Transmission electron microscopy confirmed the formation of vesicles by dilution. The membrane fluidity of the vesicles showed an ordered gel phase. The results suggest that bicelles can form vesicles by continuous dilution. This method is suitable for encapsulating materials.