Electrophoresis-assisted single-cell electroporation for efficient intracellular delivery

Single-cell electroporation, in which a focused electric field is applied to permeabilize an individual target cell using relatively low applied voltages, has demonstrated improved cell viability and transfection rates over conventional bulk electroporation set-ups. Here, we introduce a new strategy, in conjunction with single-cell electroporation, to enhance exogenous transport efficiency: electrophoresis delivery of compounds subsequent to electroporation. Electrophoresis is used to assist loading of otherwise impermeable exogenous anionic fluorescent molecules Calcein (Invitrogen, MW=622) and Oregon Green Dextran (OGD, Invitrogen, MW=70,000). For the larger dextran molecules, we demonstrate a protocol of first pre-concentrating at the cell-microfluidic channel interface. Then, the electric field is used to drive these molecules into the cell post-electroporation using 50-200 mV. We demonstrate delivery rate enhancements of more than an order of magnitude using electrophoresis compared to diffusion alone subsequent to electroporation.