Reagent Handling and Delivery System Using Cell-Sized Liposomes

We aim to construct a reagent handling system of ultra-small volume on the scale of pl to fl using giant unilamellar vesicles (GUVs) as cell-mimetic containers. Although reagent mixing and reaction by fusion and aliquoting by division of GUVs were demonstrated in our previous study [1], [2], it was difficult to control the enclosed volume since the lipid membrane is extremely soft. In this report, we show that by enclosing the hydrogel it is possible to increase mechanical strength [3] and to control the solution amount depending on the gel size. We confirmed that, upon liposome fusion, the internal solutions were mixed while the encapsulated gel retained its original shape. It is also possible to release encapsulated molecules by membrane destruction caused by the electrical stimulation. The liposome-based system has an advantage that it could be directly used in vivo or in aqueous environment, whereas reaction products need to be extracted from the oil in the emulsion droplet system.