Using DNA as a nanoscale 3D printer

Our lab shows the amazing promise of DNA based nanotechnology.

DNA is a fantastic material. It's information-rich, small in size and it glues itself together in a very predictive way. Using these three attributes, many researchers around the globe are able to produce nanoscale structures that build themselves in test-tubes by simply mixing different types of DNA molecules. Building with DNA has been around for a few years, but now komplex 3D shapes can be routinely produced: design your desired 3D nanostructure on your computer, order the DNA, mix it with some magnesium salt, heat it up, cool it down and pour out your creation.

DNA hybridization is the key

Each of the DNA bases A,T,C and G tend to want to be paired to another DNA base. All T's want to be paired with an A and all C's with a G. So if the DNA strand AGGGTGCATTC finds the strand GAATGCACCCT this will happen:

We say that the strands hybridize with each other. Note that the strands have different directions, a DNA strand will only pair with a strand that is lying in the opposite direction. The product of the hybridization reaction is a DNA double helix. A 3D view of the above reaction will conceptually look something like this:

As you can see 11 bases is approximately what it takes for the DNA spirals to take a full turn  (actually the number is closer to 10.5 bases).

Now, lets say we would like to glue together two parts of a DNA molecule and the two parts are not complementary, can we do this? There is a trick we can use, lets design a smaller DNA molecule that have regions that are complementary to the two regions and use this to bring the two parts of the longer molecule together. Like this:

In this figure, the white strand is the one we would like to glue together. The yellow strand is the strand we designed so that it would bind the two regions of the white strand together. As you can se, it is possible to fold any DNA strand with the help of another strand.

Additional info:

- Shawn made some very nice videos explaining the technique. Tutorial #1 on this page is a good introduction for a semi-professional.