DNA 'Cages' to Facilitate Nanoparticle Self-Assembly

One of the many goals of nanotechnology is to make microscopic particles come together inside living organisms, so as to form transistors, metamaterials, or even microscale robots in designated locations, which cannot be reached with larger materials. But one of the main problems of self-assembly has been the fact that nanoparticles tend to come together as a clump, instead of forming ordered structures. Over the years, experts have tried to fix this problem in a number of ways, and it seems like they may have just succeeded, thanks to a new method developed at the University of Michigan in Ann Arbor (UM).

One of the solutions that was attempted in the past was to use DNA-plated nanoparticles. The DNA would make the particles come together, but the problem of lumps still persisted. Now, UM researchers Alexei Tkachenko and Nicolas Licata believe they may have found the answer to this dilemma. They have created a new system of moving nanoparticles around, namely inside little, tetrahedron-shaped DNA “cages.” These cages are relatively hard to produce, but offer amazing results.

Basically, each of the bars in the cage is made up of a single DNA strand, but which ends with a single, chipped helix at one extremity, instead of two. Because this helix consists of proteins that only combine with opposite ones, the researchers can manipulate another DNA strand into position, and then another one, and so on. In the end, the nanoparticle becomes trapped inside a DNA pyramid, on which all extremities have a helix sticking out, which allows them to be united with other similar structures.

Because the tetrahedrons only selectively combine with other pyramids, the risk of lumps appearing is drastically reduced. The nanoparticles inside these structures then move in closer and combine with each other, forming the first building block of the new device, to be “born” inside a living tissue. In the future, the researchers envision a computer program to analyze a device sketch and then establish what type of DNA is needed, and also show how it's manufactured.

If the research is successful, the innovation could also have applications in areas other than medicine. It may then become possible to build nano-circuits and even better metamaterials, and a new field in the construction industry will be open.