Using a micro electroporation chip to determine the optimal physical parameters in the uptake of biomolecules in HeLa cells.

In this study, a new micro electroporation (EP) cell chip with three-dimensional (3D) electrodes was fabricated by means of MEMS technology, and tested on cervical cancer (HeLa) cells. Extensive statistical data of the threshold electric field and pulse duration were determined to construct an EP "phase diagram", which delineates the boundaries for 1) effective EP of five different size molecules and 2) electric cell lysis at the single-cell level. In addition, these boundary curves (i.e., electric field versus pulse duration) were fitted successfully with an exponential function with three constants. We found that, when the molecular size increases, the corresponding electroporation boundary becomes closer to the electric cell lysis boundary. Based on more than 2000 single-cell measurements on five different size molecules, the critical size of molecule was found to be approximately 40 kDa. Comparing to the traditional instrument, MEMS-based micro electroporation chip can greatly shorten the experimental time.