ABSTRACT The development of methods for detecting specific nucleic acids is important for early diagnosis and treatment of diseases at the genetic level. We have developed a pair of pyrene (Pyr)‐modified peptide nucleic acids (PNAs), PNA twin probe, as a tool for such detection. In this study, we prepared Pyr‐PNAs containing chloroacetyl (‐COCH 2 Cl) or thiol (‐SH) groups at the termini by solid‐phase peptide synthesis. By analyzing various candidates, we clarified that a pair of Pyr‐PNAs, each containing an SH group, formed a disulfide bond through the hybrid formation of two PNAs with complementary DNA, resulting in excimer emission at 455 nm. Furthermore, we demonstrated that these Pyr‐PNAs provide fluorescent detection of intracellular target RNAs through enhanced excimer emission via the ligation. This work should aid future studies aimed at the specific fluorescent detection of RNA in living cells.
Ouchi et al. (Fri,) studied this question.