Fig. 1.

Application of DNA scaffold for the detection of COVID 19. a) DNA scaffold synthesis, b and c) DNHCR based sensing of COVID 19. (FAM and BHQ1 are fluorescent dye and fluorescence quencher, respectively. Rolling circle replication (RCA) is a process in which DNA copies are produced. Tail T1 in H1 is complementary to C2 in H2, and tail T2 in H2 is complementary to C1 in H1. In the presence of RNA of SARS-CoV-2, it will hybridize with T1 and S, causing H1 to unfold to restore fluorescence (Scheme 1b II), and then H2 will hybridize with C1 and S′, causing H2 to unfold (Scheme 1b III) and continue to hybridize with adjacent H1 along the DNA nanoscaffold (Scheme 1b IV). Meanwhile, due to the compact arrangement of H1 on the DNA nanoscaffold, one target RNA can instantly light up the whole nanoscaffold with highly amplified signal gain (Scheme 1c).) (Copyright Science direct, 2020, reprinted with permission from Ref. [37], (License number: 4970230653752).