Figure 3. Demonstration that formamide can significantly accelerate toehold-mediated strand exchange reaction inhibited by small scale self-folding structures.
(A) Scheme of toehold mediated strand exchange reaction triggered by Tlinear, Tstructured1, and Tstructured2, respectively. The three triggers hold the same linear sequence of Tlinear that could displace Q5 away from F5. The segment in red was toehold binding domain, which was partly blocked in Tstructured1 and Tstructured2 at different degrees. After strand exchange, fluorescence of FAM on F5 was quenched by the Quencher on Q5. (B) and (C) Real-time fluorescent kinetic monitoring right after Tlinear, Tstructured1, or Tstructured2 was added into F5-Q5 duplex solution without (B) and with (C) 25% formamide. The experiments were carried out at 25 °C.