Simultaneous DNA amplification and detection using an electrode array

We demonstrate herein the implementation of in-situ electrochemical (EC) detection method in a microfluidic flow-through PCR device, where both the amplification of the target nucleic-acid sequence and subsequent EC detection of the PCR amplicon are realized simultaneously at selected PCR cycles in the same device. Our EC detection method is advantageous, when compared to other existing EC methods for PCR amplicon analysis, since our method does not require probe-modified electrodes, or asymmetric PCR, or solid-phase PCR. Key technical issues related to surface passivation, electrochemical measurement, bubble-free PCR, are investigated. By controlling the concentration of MB and the exposure of PCR mixture to the bare metal electrode, we successfully demonstrate electrochemical measurement of MB in solution-phase, symmetric PCR by amplifying a fragment of lambda phage DNA.