分子ロボットへの応用を目指した，マイクロ流体デバイスによるリポソームの機械的特性評価

抄録

The liposomes have been focused on as the packages of the molecular robots that change their shape by using the actuator molecules such as molecular motors, DNA, RNA, or any other added substance. To achieve the desired change in shape using the small force generated by these actuator molecules, it is crucial to understand the mechanical properties of the liposomes. For evaluating the mechanical properties of the liposomes, we applied a microfluidic device because microfluidic devices can trap and hold multiple liposomes quickly and simultaneously without skilled techniques. The microfluidic device consisted of multiple evaluation areas that connect in series. The evaluation areas were rectangular-shaped funnel channels designed to mimic the shape of the micropipette used in the micropipette aspiration method. The funnel width was approximately 5 μm. When the liposome suspension was introduced into the microchannel, each funnel trapped a single liposome. The membrane tensions of the liposomes were calculated from the deformation of the liposomes. The liposomes were prepared by the water-in-oil (W/O) emulsion method with a composition of POPC : DOPG : Cholesterol = 9 : 1 : 1. We confirmed that 20 funnels could trap liposomes, with a success rate was 45% (in one device). The average membrane tension of three liposomes was 0.40 ± 0.08 mN/m. By estimating the force of molecular actuators required for the formation of the tube structure using derived membrane tension, we demonstrated the effectiveness of the microchannel as a tool for developing molecular robots.