The intrinsic electrochemical activity of single strand deoxyribonucleic acid (ssDNA) is investigated with a micro three-electrode system (MTES) integrated inside an in situ electrochemical detection μPCR (EC-μPCR) chip. Based on the MTES, electrochemical cyclic voltammetry (CV) was performed with both normal ssDNA and special ssDNA(Guanine absence) solutions. Experimental results showed that the MTES can directly detect the electrochemical oxidation of the guanine in ssDNA. After a prepolarization step with a positive potential (+500 mV) applied to the MTES for 15 minutes, the electrochemical oxidation peak current of normal ssDNA can be increased about 40%. The detection limit of the MTES with CV method for normal ssDNA is down to 45 nM. The results reveal that label-free and real-time detection of PCR amplicons by directly monitoring the electrochemical oxidation of ssDNA is promising.
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