Reverse transcription loop-mediated isothermal amplification combined with nanoparticles-based biosensor for diagnosis of COVID-19

Given the scale and rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, known as 2019-nCov) infection (COVID-19), the ongoing global SARS-CoV-2 outbreak has become a huge public health issue. Rapid and precise diagnostic methods are thus immediately needed for diagnosing COVID-19, providing timely treatment and facilitating infection control. A one-step reverse transcription loop-mediated isothermal amplification (RT-LAMP) coupled with nanoparticles-based biosensor (NBS) assay (RT-LAMP-NBS) was successfully established for rapidly and accurately diagnosing COVID-19. A simple equipment (such as heating block) was required for maintaining a constant temperature (63 C) for only 40 min. Using two designed LAMP primer sets, F1ab (opening reading frame 1a/b) and np (nucleoprotein) genes of SARS-CoV-2 were simultaneously amplified and detected in a one-step and single-tube reaction, and the detection results were easily interpreted by NBS. The sensitivity of SARS-CoV-2 RT-LAMP-NBS was 12 copies (each of detection target) per reaction, and no cross-reactivity was generated from non-SARS-CoV-2 templates. Among clinically diagnosed COVID-19 patients, the analytical sensitivity of SARS-CoV-2 was 100% (33/33) in the oropharynx swab samples, and the assay9s specificity was also 100% (96/96) when analyzed the clinical samples collected from non-COVID-19 patients. The total diagnosis test from sample collection to result interpretation only takes approximately 1 h. In sum, the RT-LAMP-NBS is a promising tool for diagnosing the current SARS-CoV-2 infection in first line field, public health and clinical laboratories, especially for resource-challenged regions.