Electrofusion Device With High-Aspect-Ratio Electrodes for the Controlled Fusion of Lipid Vesicles

Giant liposomes or giant vesicles have been used as dynamic bioreactors because of their ability to fuse with other vesicles to mix their contents. Among various principles, electrofusion is particularly useful because it is quick and does not require solution exchange. In conventional vesicle fusion methods, quantitative evaluation of fusion events has often been difficult because vesicles float and move due to the unexpected flow. In this study, we developed a microfluidic device equipped with microchambers for structural trapping and electrodes for vesicle fusion, in which the fusion phenomenon can be observed in definite locations. Specifically, we fabricated an electrofusion device that had conductive silicon electrodes and PDMS microchambers that held giant unilamellar vesicles (GUVs; diameter $\gt 6~\mu $ m) in place. The fusion yield of GUV-GUV and GUV-small GUV (diameter $\lt 2~\mu $ m) was examined by detecting the fluorescence marker that appeared upon the mixing of internal contents of two vesicle populations. This architecture can be used to realize parallel electrofusion assays for quantitatively analyzing biochemical reactions in the cell-mimetic environment. [2024-0166]