Manipulating self-assembled phospholipid microtubes using microfluidic technology

A stable method for the manipulation of phospholipid microtubes was established. Based on MEMS technology, microfluidic technology and lipid hydration, a series of phospholipid microtubes, 1-10 μm in diameter, were manufactured from dried thin phospholipid films in the microchannel, in an efficient manner. The single 1,2-dimyristoyl-sn-glycerol-3-phosphcholine (DMPC) microtube was formed along the flow direction under the condition of 100 mg/mL phospholipids, 20 °C reaction temperature, pH 5.5 of the buffer, 30 s hydration time and 50 μL/min flow speed. When the flow rate exceeds 50 μL/min and the concentration of the phospholipids exceeds 150 mg/mL, the multi-tubules phenomena together with some self-organizing lipid networks and tubule-vesicle systems can be observed in most experiments. The double-helix phenomenon of the phospholipid microtube was observed when the flow rate was less than 50 μL/min or the pumping broke off suddenly. In addition, the microtubes would not be generated, and sometimes tubules were broken, when the flow rate exceeded 1000 μL/min. The parameters of the microfluidic system, having an influence on the phospholipid microtubes generation, were optimized to result in values of flow rate between 50 and 200 μL/min, hydration temperature exceeds the phase transition temperature within 20 °C, pH of the aqueous solution is 5.5 and phospholipids concentration is 100 mg/mL. Utilizing “two times replicated method”, we could rapidly fabricate epoxy microchip with good mechanical properties. Our device was easy and convenient to operate, and low-cost to fabricate. Our strategy, utilizing microfluidic technology, has the advantages of large growth and self-alignment, together with some interesting lipid network systems.