Low-Voltage Flow-Through Electroporation in Gold-Microtube Membranes

Electroporation is used to create pores within the membrane of living cells in order to deliver a substance, for example, a gene, into the cytoplasm. To achieve the high electric field gradients required to porate the membrane, current electroporation devices deliver voltage pulses in the kV range to the cell medium. We describe a new device based on gold-microtube membranes that can accomplish electroporation with voltage pulses that are orders of magnitude smaller, ≤5 V. This is possible because the voltage pulses are applied to the gold microtubes resulting in large electric field gradients down the length of the tubes. We used COMSOL simulations to calculate the electric field gradients, and these theoretical results were compared with known experimental values required to electroporate Escherichia coli. We developed two fluorescence-based methods to demonstrate successful electroporation of E. coli. The percentages of electroporated bacteria were found to be more than an order of magnitude higher than obtained with a commercial electroporator, although the voltage employed was 500 times lower. Furthermore, this microtube membrane device is flow through and is therefore capable of continuous, as opposed to batch-wise, electroporation and cell analysis. Cell throughput of >30 million cells per min, higher than any previously reported device, were obtained.