Fabrication of nano-scale liposomes containing doxorubicin using Shirasu porous glass membrane

Nano-scale liposomes were successfully produced using a Shirasu porous glass (SPG) membrane emulsification technique. Primary liposomes prepared by a film-hydration method were treated using SPG membranes with different pore sizes (2.0, 1.0, 0.7, 0.5, and 0.2 μm) for control over the liposome size. The liposome sizes were evaluated using a dynamic light scattering method and their morphologies were observed by optical microscopy and transmission electron microscopy. As the passage number of liposomes through SPG membrane increased, the size and its distribution of the liposomes gradually decreased. A smaller pore size of the SPG membrane and a higher applied pressure resulted in liposomes with a smaller size. After the preparation of nano-scale liposomes containing ammonium sulfate (AS), doxorubicin (DOX) was encapsulated in the liposomes by a remote loading method, where AS served as a precipitant for DOX. The encapsulation efficiency of the DOX was maximized up to 94% when the concentrations of AS and DOX were 250 and 0.045 mM, respectively. We have obtained the release profiles of the liposomes with different sizes. As shown below, liposomes with smaller size exhibited a faster release profile of drug due to the large surface area. These nano-scale liposomes encapsulating an anti-cancer drug can potentially be employed as drug delivery vehicles for intravenous injection.

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► Nano-scale liposomes were successfully produced using a SPG membrane emulsification method.
► An increase in passage number through SPG membrane led to reduction in liposome size.
► A smaller pore size of SPG membrane and a higher applied pressure resulted in smaller liposomes.
► The size reduction was due to both the friction and collision of liposomes against pore wall.
► Doxorubicin was encapsulated into the nano-scale liposomes by a remote loading method.