Label-free and Electrochemical Detection of Nucleic Acids Based on Isothermal Amplification in Combination with Solid-state pH Sensor

Label-free quantification methods for nucleic acids are attracting attention, since they provide potential tools in clinical applications such as disease diagnosis or prognosis observation. In this research, we developed a simpler and cost-effective electrical monitoring device of nucleic acid amplification, combining an isothermal amplification method and an Iridium/Iridium oxide (Ir/IrOx) electrode without labeling. The fabricated Ir/IrOx electrode showed ideal Nernstian response under the various pH buffer solutions, and its potential response was less affected even in the presence of charged proteins. Moreover, we successfully real-time monitored primer generation-rolling circle amplification (PG-RCA) at the 0, 10, 100, 1000 pM of target DNA by detection of released proton during amplification reaction at the constant reaction temperature. This label-free and portable device might be received considerable attention as a useful platform for a point-of-care testing in clinical use.