Rectangular Box Container Design
Figure 1. A CanDo
model of a component of our rectangular box.
Andersen's box impressed us with its ability to open and close, but we worried about its robustness and tightness as a container.
- Cryo-EM imaging performed by Andersen revealed that the faces are either bent inward or outward.
- Furthermore, the Andersen box is formed from a one-layer DNA sheet and, as such, is held together by five potentially weak seams.
Therefore, with the help of Wei Sun, we have designed our own box, which we feel stands a much better chance of keeping cargo inside and which is more straightforward to fold and to characterize.
See also: Rectangular Box Results, Rectangular Box Methods
Spherical Container Design
Figure 2. A three-dimensional model of the Han sphere (Han et al. 2011).
In our search for a robust and elegant design, we were inspired by the origami sphere that Dongran Han demonstrated in his 2011 Science paper "DNA Origami with Complex Curvatures in Three-Dimensional Space" (Figure 2).
The spherical design appealed to us because of its efficient use of DNA and lack of weak points--that is, instead of having edges, it only has two holes at each pole, minimizing spots where cargo can leak out.
We changed the design of the Han sphere to make it an openable and closable container. To open the sphere, we removed all staple strands holding its two hemispheres together; to close the sphere, we designed a system of locks; and to re-open the sphere, we designed strand displacement and photocleavage mechanisms.
See also: Sphere Results, Sphere Methods
Figure 3. We conjugated ssDNA strands to 5 nm gold nanoparticles. We could attach a single ssDNA strand, or multiple ssDNA strands, per nanoparticle.
With a few container designs in mind, our next goal was to provide them with functionality.
- We use 5-nm gold nanoparticle cargo as a test platform for our ability to capture, contain, and controllably release cargo.
- We chose 5-nm gold nanoparticles because the sharp contrast they provide under TEM helps us to classify our results easily.
Cargo in the Sphere, Cargo in the Box, Nanoparticle Results, Photocleavage Results