Though they’ve never actually seen it with their own eyes, scientists know that DNA’s structure is composed of a spiraling corkscrew. They know this thanks to molecular theory and and an old-time technique called X-ray crystallography, where patterns of dots are converted into an overarching image using mathematics. But now, for the first time ever, scientists have actually snapped a real image of DNA using an electron microscope — spiraling corkscrew and all.
The image was taken by Enzo di Fabrizio from the University of Genoa, Italy. He choreographed the scene by pulling a small strand of DNA from a diluted solution and then propping it up like a clothesline between two nanoscopic silicon pillars.
The trick to the technique was in acquiring a discrete strand of DNA that could be stretched out and ready to view with an electron microscope. Di Fabrizio managed this by creating a pattern of pillars that repelled water — which resulted in quick moisture evaporation and a residual strand of DNA all ready to go.
Then, in order to create a high-resolution image, di Fabrizio drilled tiny holes in the base of the nanopillar bed and shone beams of electrons.
Aside from creating a cool image, the technique will allow the researchers to investigate DNA in greater detail, as well as seeing how it interacts with proteins and RNA.
The paper, “Direct Imaging of DNA Fibers: The Visage of Double Helix,” was published in Nano Letters.
Supplementary source: New Scientist.