The design of dynamic, reconfigurable devices is crucial for the bottom-up construction of artificial biological systems. DNA can be used as an engineering material for the de-novo design of such dynamic devices. A self-assembled DNA origami switch is presented that uses the transition from double- to single-stranded DNA and vice versa to create and annihilate an entropic force that drives a reversible conformational change inside the switch. It is distinctively demonstrated that a DNA single-strand that is extended with 0.34 nm per nucleotide – the extension this very strand has in the double-stranded configuration – exerts a contractive force on its ends leading to large-scale motion. The operation of this type of switch is demonstrated via transmission electron microscopy, DNA-PAINT super-resolution microscopy and darkfield microscopy. The work illustrates the intricate and sometimes counter-intuitive forces that act in nanoscale physical systems that operate in fluids.

中文翻译：

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双链到单链跃迁在 DNA 折纸纳米结构中诱导力和运动

动态、可重构设备的设计对于人工生物系统的自下而上构建至关重要。DNA 可用作这种动态装置的从头设计的工程材料。提出了一种自组装的 DNA 折纸开关，它利用从双链 DNA 到单链 DNA 的转变（反之亦然）来产生和消除驱动开关内部可逆构象变化的熵力。明显地证明，每核苷酸延伸 0.34 nm 的 DNA 单链——这条链在双链结构中的延伸——在其末端施加收缩力，导致大规模运动。这种开关的操作通过透射电子显微镜、DNA-PAINT 超分辨率显微镜和暗场显微镜进行了演示。