Enzyme-Powered Three-Dimensional DNA Nanomachine for DNA Walking, Payload Release, and Biosensing.

Herein, we report a DNA nanomachine, built from a DNA-functionalized gold nanoparticle (DNA-AuNP), which moves a DNA walker along a three-dimensional (3-D) DNA-AuNP track and executes the task of releasing payloads. The movement of the DNA walker is powered by a nicking endonuclease that cleaves specific DNA substrates on the track. During the movement, each DNA walker cleaves multiple substrates, resulting in the rapid release of payloads (predesigned DNA sequences and their conjugates). The 3-D DNA nanomachine is highly efficient due to the high local effective concentrations of all DNA components that have been co-conjugated on the same AuNP. Moreover, the activity of the 3-D DNA nanomachine can be controlled by introducing a protecting DNA probe that can hybridize to or dehybridize from the DNA walker in a target-specific manner. This property allows us to tailor the DNA nanomachine into a DNA nanosensor that is able to achieve rapid, isothermal, and homogeneous signal amplification for specific nucleic acids in both buffer and a complicated biomatrix.