Study of gene transfection enhancement and parameters optimisation using electroporation microchip

A design for improving gene transfection efficiency, which provides simple fabrication, low voltage and power consumptions, and easy implementation is developed; this design entails combining high and low electric fields, adjusting the voltage, using different numbers of pulses with varying durations, and different types of buffers with differing conductivities. The human embryonic kidney 293 (293T) cells were used. It was shown that a combination of two units of high electric field (1600 V/cm) for 0.6 ms and three units of low electric field (800 V/cm) for 1.2 ms is the optimum combination. This combination yielded a survival rate greater than 70% and a transfection rate of approximately 45%. The transfection rate of this combination was 80–100% greater than that obtained using two pulses, and the transfection rate obtained using two pulses was 40–50% greater than that obtained using single pulses. However, the survival rate decreases when the pulse duration is considerably long, even for low electric fields; therefore the number of pulses and their durations should be limited. The hypoosmolar buffer yielded the largest transfection rate. It was shown that the conductivity of the buffer solution is an important parameter, with the appropriate value ranging within 1.0–3.6 mS/cm. The transfection rate of the 293T cells using a cytoporation buffer could be enhanced by adding potassium ions in concentration lower than 2 μg/ml.