Electrochemical real-time monitoring of isothermal nucleic acid amplification for quantitative analysis

Label-free miniaturized electrochemical devices have been developed to monitor the nucleic acid amplification. We successfully monitored released protons during amplification reaction in real-time manner using miniaturized pH sensors and demonstrated quantitative detection of nucleic acid. Because the sensitivity of ion-sensitive field effect transistor (ISFET) (-58.0 mV/pH) and iridium/ iridium oxide (Ir/IrOx) electrode (-57.4 mV/pH) as a pH sensor showed close values to theoretical value (-59.2 mV/pH), the combination between isothermal nucleic acid amplification and the electrochemical detection was compatible with potentially stable measurement. The proposed system would be cost-effective and portable, and potentially implemented in clinical use such as diagnosis of infectious disease and cancer.