Active Devices

An important domain of molecular robotics encompasses devices that can cycle through different states to create behaviors such as locomotion and computation. This requires systems that work out-of-equilibrium; potential mechanisms include kinetically controlled consumption of building blocks for autonomous operation and pulses of energy delivered from external sources for clocked operation.

single molecule clock dna nanotechnology

image credit Alexander Johnson-Buck 

Schematic for a general approach for the design of single-molecule clocks that permits quasi-deterministic control over the lifetime of single molecular interactions without any external synchronization. Nano Letters 2017 17 (12), 7940-7944.

In the area of autonomous operation, we are especially interested in exploring DNA-based devices driven by enzymatic or crisscross polymerization. In the area of clocked operation, we investigate DNA-based devices that can be thermal cycled based on competitive hybridization, and devices that can be cycled via sequential strand replacement using microfluidics. We also seek to engineer control over our systems with other means, such as optical-, magnetic-, or tension- based actuation. In collaboration with the groups of Tim Liedl at LMU and Andrew Turberfield at U. Oxford, we're developing controlled stepping towards nanoscale DNA-based printers.

Schematic of proposed DNA-origami-based printers.

Key Publications:

Hahn J, Shih WM. Thermal Cycling of DNA Devices via Associative Strand Displacement. Nucleic Acids Res. 47, 10968–10975, 2019. [zip]  

Hahn J, Chou LYT, Sørensen RS, Guerra RM, Shih WM. Extrusion of RNA from a DNA-Origami-Based NanofactoryACS Nano. 14, 1550–1559, 2020. [zip]  

Johnson-Buck A, Shih WM. Single-Molecule Clocks Controlled by Serial Chemical ReactionsNano Lett. 17, 7940–7944, 2017 [zip]