We designed DNA structures that can represent three states: “6-vertex structure”, “8-vertex structure”, and “diamond dodecahedron structure (intermediate)”. Among these three states, the 6-vertex and 8-vertex structures are somewhat fixed in structure by fastening DNA and have a more stable structure than the intermediate. Therefore, we thought that two different roles could be assigned to the “6-vertex structure” and “8-vertex structure” in the future. Below, we summarize specific examples of their applications.

First, as an application that can be realized in the near future, we focused on the vertex part of the structure. Our structure can take a form in which six vertices and eight vertices protrude. Therefore, by attaching a chemical substance to this vertex part, the structure can have a function of using two properties arbitrarily. Also, if a chemical substance is attached only to one set of vertices, for example, only six vertices, it is expected that it will be active when six vertices protrude and inactive when eight vertices protrude because the chemical substance is hidden.

Fig.1 the alteration of substances exposed on the surface due to structural changes

The problem when considering such applications is thought to be the existence of an intermediate. The intermediate is essential because it has a reversible structure, but if it stays in the intermediate state for a long time, specific chemical activity attached to the 6-vertex and 8-vertex structures will be lost. Therefore, there are technical challenges such as how to switch between 6-vertex and 8-vertex structures quickly in the future or how to minimize the time taken for intermediates.

Next, changes in the trigger part of the opening and closing mechanism can be considered. Currently, chain substitution reactions using ssDNA are used, but by changing to chain substitution reactions using I-motifs[1] that react to pH, structural changes according to changes in pH become possible. Therefore, we believe that this structure can ultimately serve as an external sensor for molecular robots that convert changes in nano-scale environments into signals that can be recognized as structural changes.

Fig.2 application for biosensor

The problem is likely to be the sensitivity of the sensor. In our structure's deformation mechanism, deformation that is assumed not to occur unless all triggers react does not occur. Therefore, measures such as reducing the scale of the entire structure and bringing all sensor positions closer together are necessary to increase sensitivity.