Site-specific enhancement of gene transfection utilizing an attracting electric field for DNA plasmids on the electroporation microchip

Site-specific enhancement of in vitro gene delivery using electrostatic force and ElectroPoration (EP) microchips is analyzed in this study. Electroporation is a technique that introduces foreign materials into cells by applying impulses with an electric field to create multiple transient pores in the cell membrane through a dielectric breakdown of the cell membrane. The electroporation chip employed in this process consists of a defined cell culture cavity region with thin film electrodes made of titanium and gold, and was fabricated on a glass slide using microfabrication technologies. Four μg of DNA plasmids were added into the well of the microchip prior to electroporation. The electric field for attracting DNA was generated using a gold plate electrode on the top of the cell culture cavity, and one side of interdigitated electrodes. As the anode was connected to one side of the interdigitated electrodes, the negative-charged DNA plasmids were attracted and accumulated at the finger electrodes with positive polarity, thereby increasing the DNA concentration on the surface of these powered electrodes. After the DNA plasmids were accumulated, the electric power was switched to the interdigitated electrodes to perform the cell electroporation process. This paper investigates the DNA concentration during electrophoresis on the micro electroporation chip, based on a one-dimensional (1-D) steady-state approximation and a two-dimensional (2-D) transient simulation. This study demonstrates that the attracting electric field increases the concentration of negative-charged DNA plasmids near the cell surface up to several thousand-fold prior to electroporation, which enhances the gene transfection efficiency up to 6.3-fold compared to that without an attracting electric field. The pEGFP-N1 plasmids coding for green fluorescent protein (GFP) were transfected into an osteoblast-like cell line (MC3T3E-1) to exhibit the site-specific and enhanced gene delivery on the microchip. The experiments of in vitro gene transfection on a microchip successfully verified the numerical study in this paper. The most important issue of gene therapy is to develop a site-specific gene delivery platform for the controlled expression of transgenes in specific cells or tissues. This present work successfully demonstrates the enhancement and site-specific transfection utilizing the attracting electric field on an electroporation microchip.