Make smart DNA-based machines
Zhen-Gang Wang, National Center for Nanoscience and Technology
The construction and operation of DNA-based molecular machines have attracted much attention. The activation of DNA machines originates from the responsive conformation of DNA molecules, which is transferred into the complicate motions. In this presentation, I will show some recent efforts on the logical operations of the artificial machines, aiming to elevate the complexity of the machines and the ability of thinking.
We developed a tweezers system that included three tweezers and each designed to recognize different target molecules or ions. Therefore, the three tweezers can be closed or opened by the respective fuels (i.e. recognized substrate). The fuel pairs included Hg2+/cysteine, H+/OH-, DNA/its complementary strand. The alternative addition of the fuels activated the two or three tweezers concurrently, establishing the communication between the tweezers. As a result, a SET/RESET logic system or a finite state automation system was constructed and operated autonomously, with multiple inputs and outputs. Especially, the latter one exhibits a feature of memory. Using the similar fueling mechanism, we constructed DNA-based walker system, including the bipedal walking device and a track. The walker was driven to move forward or backward along the track by the fuels of Hg2+/cysteine and H+/OH-.
To improve the programmability of the DNA machines, we constructed a model machine that was able to transport a molecular cargo clockwisely or anticlockwisely. The function depends on the arm sequence of the machine. Like a screwdriver, upon replacing one arm with another, the transporter functioned in a different way. Moreover, the arm could be replaced during the working of the machine. That means, the function of the DNA machine was programmed dynamically.
I also would like to introduce a mechanically interlocking DNA nanostructure, catenanes. We synthesized the catenanes composed of two or three single stranded DNA rings and demonstrated the directional movement of the ring components by controlling the conformation of the route. Therefore, the catenanes can undergo programmed and reversible reconfiguration across defined topologies.