Dimension Control of Glycolipid Nanotubes by Successive Use of Vesicle Extrusion and Porous Template

We have developed a rapid and convenient method to prepare lipid nanotubes (LNTs) with defined diameters. Extrusion of the aqueous dispersion of a glycolipid N- (11- cis- octadecenoyl)-β - d -glucopyranosylamine at 90 °C through a polycarbonate (PC) filter (100 nm pore size) produced uniform vesicles with thin walls. The extruded vesicles were filled into the nanopores of an anodic alumina membrane (AAM) filter (200 nm pore size) and then self-assembled into tubular structures within the nanopores on cooling. This method enabled us to narrow the distribution of outer diameters, inner diameters, and wall thickness of the resultant LNTs. The mean outer diameter of the LNTs was 148 nm, approaching the pore size of the PC filter used for the extrusion. The extrusion through the 100 nm PC filter effectively reduced the mean wall thickness of the LNTs to 48 nm.