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

Xiong Zhu; Xiaoxia Wang; Limei Han; Ting Chen; Licheng Wang; Huan Li; Sha Li; Lvfen He; Xiaoying Fu; Shaojin Chen; Xing Mei; Hai Chen; Yi Wang

The copyright holder for this preprint . https://doi.org/10.1101/2020.03.17.20037796 doi: medRxiv preprint row). These results indicated that F1ab-and np-LAMP primer sets were available for 174 establish the COVID-19 RT-LAMP NBS assay for rapid and reliable detection of 175 SARS-CoV-2. The parameter of optimal temperature for COVID-19 RT-LAMP 176 technique also was tested, and reaction temperature of 63°C was used for performing 177 the COVID-19 RT-LAMP amplification (Figure S2 and S3) . The COVID-19 RT-LAMP-NBS was able to detect down 12 copies (each of 181 F1ab-plasmid and np-plasmid) (Figure 4) . Two target genes were detected and 182 identified in a one-tube reaction ( Figure 4A) . The COVID-19 RT-LAMP results 183 using NBS were in consistent with turbidity and VDR detection (Figure 4B and 4C) , 184 while traditional monitoring techniques (VDR and turbidity) could not facilitate 185 multiplex analysis. Furthermore, the sensitivity of COVID-19 RT-LAMP-NBS assay 186 was in conformity with F1ab-and np-RT-LAMP assay (Figure 4, S4 and S5) . 187 The optimal duration time of COVID-19 RT-LAMP-NBS assay at the isothermal 188 stage also was determined, and the template level at the detection limit appeared three indicating no cross-reaction with non-SARS-CoV-2 templates (Table S2) .