Toehold-mediated strand displacement (TMSD) is an isothermal switching process that enables the sequence-programmable and reversible conversion of DNA or RNA strands between single- and double-stranded conformations or other secondary structures. TMSD processes have already found widespread application in DNA nanotechnology, where they are used to drive DNA-based molecular devices or for the realization of synthetic biochemical computing circuits. Recently, researchers have started to employ TMSD also for the control of RNA-based gene regulatory processes in vivo, in particular in the context of synthetic riboregulators and conditional guide RNAs for CRISPR/Cas. Here, we provide a review over recent developments in this emerging field and discuss the opportunities and challenges for such systems in in vivo applications.

Toehold 介导的链置换 (TMSD) 是一种等温转换过程，可使 DNA 或 RNA 链在单链和双链构象或其他二级结构之间进行序列可编程和可逆转换。TMSD 过程已经在 DNA 纳米技术中得到广泛应用，它们被用于驱动基于 DNA 的分子设备或用于实现合成生化计算电路。最近，研究人员也开始使用 TMSD 来控制体内基于 RNA 的基因调控过程，特别是在 CRISPR/Cas 的合成核糖调节剂和条件性指导 RNA 的背景下。在这里，我们回顾了这一新兴领域的最新发展，并讨论了此类系统在体内应用。