A HiPAD Integrated with rGO/MWCNTs Nano‐Circuit Heater for Visual Point‐of‐Care Testing of SARS‐CoV‐2

Nowadays, the main obstacle for further miniaturization and integration of nucleic acids point-of-care testing devices is the lack of low-cost and high-performance heating materials for supporting reliable nucleic acids amplification. Herein, reduced graphene oxide hybridized multi-walled carbon nanotubes nano-circuit integrated into an ingenious paper-based heater is developed, which is integrated into a paper-based analytical device (named HiPAD). The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is still raging across the world. As a proof of concept, the HiPAD is utilized to visually detect the SARS-CoV-2 N gene using colored loop-mediated isothermal amplification reaction. This HiPAD costing a few dollars has comparable detection performance to traditional nucleic acids amplifier costing thousands of dollars. The detection range is from 25 to 2.5 × 1010 copies mL-1 in 45 min. The detection limit of 25 copies mL-1 is 40 times more sensitive than 1000 copies mL-1 in conventional real-time PCR instruments. The disposable paper-based chip could also avoid potential secondary transmission of COVID-19 by convenient incineration to guarantee biosafety. The HiPAD or easily expanded M-HiPAD (for multiplex detection) has great potential for pathogen diagnostics in resource-limited settings.