Fig. 4
Approaches based on oligonucleotide-templated reaction and nanobead. a Complementary Watson–Crick base-pairing between the RNA target and two engineered PNA probes catalyzes oligonucleotide-templated reaction where a fluorogenic Michael addition reaction and unleashes the quenched fluorescence of a coumarin derivative. Adapted with permission from ref. [76]. b DSN is a highly stable, nonspecific endonuclease, which possesses a strong preference for double-stranded DNA and DNA in DNA−RNA heteroduplexes. The substrate specificity of this enzyme is ideal for the development of miRNA sensing strategies. Since target-miRNA remains intact during this process, under conditions of effective enzymatic activity, target-recycling amplification leads to significant signal enhancement. Adapted with permission from ref. [77]. c Schematic illustration of miRNA capturing using magnetic nanoparticles where mix RNAt sample with Cy-3-DNA modified Fe3O4@Ag NPs concentrate samples by a magnet and add DSN for incubation after wash away the Cy-3-DNA fragments and read out Raman signal (adapted from ref. [79])
