ABSTRACT
The morphology of self-assembled phospholipid membranes (e.g., micelles, vesicles, rods, tubes, etc.) depends on the method of formation, secondary manipulation, temperature, and storage conditions. In this contribution, microfluidic systems are used to create pure phosphatidylcholine (PC) micro- and nanotubes with unprecedented lengths. Tubes up to several centimeters in length and aligned with the long axis of the microchannel were created from spots of dry films of 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC), 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC). These high aspect ratio structures, which, to our knowledge, represent the first examples of extended tubes formed from pure PC lipids, were examined by fluorescence microscopy, electron and optical microscopy, and optical manipulation tools (i.e., a laser trap and laser scalpel) to characterize structure and stability. In particular, the tubular structure was confirmed by observation of fluorescent dyes that were sequestered within the aqueous cavity or within the phospholipid tube. Compared to other phospholipid tubes, the tubes formed from PC lipids in microfluidic channels show high mechanical stability and rigidity that depend on tube size, age, and storage conditions.
