A Novel Gene Transformation Technique Using Water-in-Oil Droplet in an Electrostatic Field

Droplet-based micro total analysis systems have been investigated by many researchers and used in bioengineering. In these systems, individual water-in-oil (W/O) droplets perform as microreactors. To manipulate W/O droplets, an electrostatic field is one of the most useful tools. For example, by applying a direct current (dc) electric field between electrodes soaked in oil, W/O droplets in the electrode spacings reciprocate due to dielectrophoretic force and Coulomb force. In this paper, gene transformation to Escherichia coli cells by using the droplet recycling is carried out. A droplet containing E. coli and plasmid deoxyribonucleic acid was located between the electrodes, and dc voltage was applied. As a result, the transformants were obtained. Therefore, the gene transformation by the electrostatic droplet manipulation was confirmed. In this method, sample volume can be smaller than that of conventional method. Therefore, our novel gene transfection method is expected to be a new tool in miniaturized bioengineering.