Design and Characterization of Force-Sensitive DNA Origami Components

Abstract

Scaffolded DNA origami is powerful design and fabrication tool for the creation of nanoscale objects via bottom up self-assembly. These objects have ∼nm level geometric complexity and spatial accuracy, which is comparable to biological machinery. DNA origami has been used to create different a wide range of objects such as drug delivery containers or platforms to guide molecular robots. Current applications of DNA origami exploit the large stiffness of bundles of dsDNA to create structures that maintain a well-defined and static geometry. However, DNA origami nanostructures with mechanically functional components, such as springs or actuators have remained largely unexplored. We aim to make DNA origami devices that are responsive to force magnitudes typically seen in biomolecular system (∼picoNewtons). We have currently developed a binary approach to make force-sensitive DNA origami components and demonstrated this approach through the design of a binary force sensor. This force sensor incorporates structures similar to DNA hairpins into DNA origami designs. The hairpin-like structures undergo a conformational change at a specific force threshold. We have characterized the conformational change dynamics of this force sensor using different experimental methods including single-molecule total internal reflection fluorescence microscopy, transmission electron microscopy and magnetic tweezers. We have shown that such dynamics can be tuned according to the design to meet the requirement of a wide range of applications. An analog force sensor is also in development using similar approaches. Ultimately we aim to use these devices to measure forces of molecular interactions in cellular systems, for example cellular traction forces applied during cell migration.