Real-time monitoring of isothermal nucleic acid amplification on a smartphone by using a portable electrochemical device for home-testing of SARS-CoV-2

Home-testing of SARS-CoV-2 is an ideal approach for controlling the pandemic of COVID-19 and alleviating the shortage of medical resource caused by this acute infectious disease. Herein, a portable device that enables real-time monitoring of isothermal nucleic acid amplification tests (INAATs) through the electrochemistry method was fabricated for home-testing of SARS-CoV-2. First, a disposable plug-and-play pH-sensitive potentiometric sensor that matches this electrochemical INAATs (E-INAATs) device was designed to allow the label-free pH sensing detection of nucleic acid. By applying Nafion film on the polyaniline-based working electrode, this sensor exhibited an excellent linear potentiometric response to pH value in the range of 6.0-8.5 with a slope of-37.45 & PLUSMN; 1.96 mV/pH unit. A Bluetooth module was integrated into this device to enable the users real-time monitoring INAATs on their smartphones at home. Moreover, by presetting criteria, the detection results could be auto-matically judged by the device to avoid human errors. Finally, the utility of this E-INAATs device was demon-strated by detecting the presence of SARS-CoV-2 nucleocapsid protein gene in artificial samples with a sensitivity of 2 x 102 copies/test within 25 min, which was comparable with fluorescence and colorimetric assay. This portable, easy-operated, sensitive, and affordable device is particularly desirable for the full integration of household SARS-CoV-2 detection products and will open a new prospect for the control of infectious diseases via electrochemical NAATs.

Automated summary

Home-testing of SARS-CoV-2 is an ideal approach for controlling the COVID-19 pandemic and addressing the shortage of medical resources. A portable device was developed for real-time monitoring of isothermal nucleic acid amplification tests (INAATs) through the electrochemistry method. The device features a pH-sensitive potentiometric sensor for label-free detection of nucleic acid and a Bluetooth module for real-time monitoring on smartphones. The device demonstrated sensitivity and comparability with fluorescence and colorimetric assays.