Electroformation and electrofusion of giant vesicles in a microfluidic device

Electroformation and electrofusion of giant vesicles with diameters of 10–20 μm have been performed in a microfluidic device with high-density microelectrodes forming the sidewalls of the microchannel. Electroformation of giant vesicles by a solution mixture of phosphatidylcholine (PC) and cholesterol (Chol) with different concentrations under AC electric field was investigated. Under the conditions of 0.5–12 mg/mL PC and 0.1–2.4 mg/mL Chol, vesicles were electroformed by the AC electric field imposed. About 60% electroformed vesicles were giant (unilamellar) vesicles with diameters 10–20 μm. The eletroformed vesicles were collected from the chip, re-suspended in fresh buffer, and then separated by centrifugation to segregate the ones with desired diameters (10–20 μm). Electrofusion of the giant vesicles was conducted in the same chip. Vesicles were aligned to form pairs under AC electric field due to positive dielectrophoresis, and the paired vesicles were subsequently fused upon the application of high strength electrical pulses. The alignment and fusion efficiencies were, respectively, about 50% and 20%.