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    ABSTRACT: In order to study cell electroporation in situ, polymer devices have been fabricated from poly-dimethyl siloxane with transparent indium tin oxide parallel plate electrodes in horizontal geometry. This geometry with cells located on a single focal plane at the interface of the bottom electrode allows a longer observation time in both transmitted bright-field and reflected fluorescence microscopy modes. Using propidium iodide (PI) as a marker dye, the number of electroporated cells in a typical culture volume of 10–100 μl was quantified in situ as a function of applied voltage from 10 to 90 V in a series of \({\sim}\) 2-ms pulses across 0.5-mm electrode spacing. The electric field at the interface and device current was calculated using a model that takes into account bulk screening of the transient pulse. The voltage dependence of the number of electroporated cells could be explained using a stochastic model for the electroporation kinetics, and the free energy for pore formation was found to be \(45.6\pm 0.5\) kT at room temperature. With this device, the optimum electroporation conditions can be quickly determined by monitoring the uptake of PI marker dye in situ under the application of millisecond voltage pulses. The electroporation efficiency was also quantified using an ex situ fluorescence-assisted cell sorter, and the morphology of cultured cells was evaluated after the pulsing experiment. Importantly, the efficacy of the developed device was tested independently using two cell lines (C2C12 mouse myoblast cells and yeast cells) as well as in three different electroporation buffers (phosphate buffer saline, electroporation buffer and 10 % glycerol).
    European Biophysics Journal 12/2014; 44(1-2). DOI:10.1007/s00249-014-1001-x · 2.47 Impact Factor
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    ABSTRACT: Electroporation is a commonly used approach to rapidly introduce exogenous molecules into cells without permanent damage. Compared to classical electroporation protocols, microchip-based electroporation approaches have the advantages of high transfection efficiency and low consumption, but they also commonly rely on costly and tedious microfabrication technology. Hence, it is desirable to develop a novel, more affordable, and effective approach to facilitate cell electroporation. In this study, we utilized standard printed circuit board (PCB) technology to fabricate a chip with an interdigitated array of electrodes for electroporation of suspended cells. The electrodes (thickness ~ 35 μm) fabricated by PCB technology are much thicker than the two-dimensional (2D) planar electrodes (thickness < 1 μm) fabricated by conventional microfabrication techniques and possess a smooth corner edge. Numerical simulations showed that the three-dimensional (3D) electrodes fabricated by PCB technology can provide a more uniformly distributed electric field compared to 2D planar electrodes, which is beneficial for reducing the electrolysis of water and improving cell transfection efficiency. The chip constructed here is composed of 18 individually addressable wells for high throughput cell electroporation. HeLa, MCF7, COS7, Jurkat, and 3 T3-L1 cells were efficiently transfected with the pEGFP-N1 plasmid using individually optimal electroporation parameters. This work provides a novel method for convenient and rapid cell transfection and thus holds promise for use as a low-cost disposable device in biomedical research.
    Bioelectrochemistry 10/2014; 102. DOI:10.1016/j.bioelechem.2014.10.002 · 3.87 Impact Factor
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    European Urology Supplements 04/2014; 13(1):e362-e362a. DOI:10.1016/S1569-9056(14)60357-2 · 3.37 Impact Factor