Electroporation of cell membrane occurs when sufficiently large electric field gradients (in the order of kV/cm) are applied to a cell medium. This is routinely accomplished in medicine and biology using voltage pulses above 1 kV in order to incorporate foreign molecules and genes into living cells.¹ However, transient pore formation or reversible electroporation is a challenge with such large voltages because of Joule heating, pH changes and ion dissolution that lead to high cell mortality.² Furthermore, special safety precautions are required. As such, the miniaturization of electroporation devices has been a research interest in order to reach similar electric field gradients with lower voltages.³ It was also shown that these microscopic devices result in higher electroporation yields and better cell viability, although often reducing the cell throughput.

We have developed an electroporation system that consists on charging gold microtubes inside a filter membrane to electroporate Escherichia coli at low voltages (<5 V).⁴ Supporting our experimental results with theoretical simulations, we have shown that electric field gradients of 4 kV/cm, sufficiently large to reversibly porate the bacteria membrane, were formed inside the gold microtubes. Following the incorporation of exogenous probes inside E. coli with fluorescence microscopy and spectroscopy, we have determined that up to 40% of the bacteria were reversibly electroporated. This is more than an order of magnitude higher than the efficiency obtained with a commercial electroporation device. Finally, cell throughput of >30 million cells per minutes, higher than any previously reported device, were obtained.

1. Gehl, J. Acta Physiol. Scand. 2003, 177, 437-447.
2. Lee, W. G.; Demirci, U.; Khademhosseini, A. Integr. Biol. 2009, 1, 242-251.
3. Geng, T.; Lu, C. Lab Chip 2013, 13, 3803-3821.
4. Experton, J.; Wilson, A. G.; Martin C. R. Anal. Chem. [Article ASAP]. DOI: 10.1021/acs.analchem.6b03820. Published Online: Nov 17, 2016.