Direct imaging becomes important when the knowledge at few/single molecule level is requested and where the diffraction does not allow to get structural and functional information. Here we report on the direct imaging of double stranded (ds) λ-DNA in the A conformation, obtained by combining a novel sample preparation method based on super hydrophobic DNA molecules self-aggregation process with transmission electron microscopy (TEM). The experimental breakthrough is the production of robust and highly ordered paired DNA nanofibers that allowed its direct TEM imaging and the double helix structure revealing.
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.
Awesome. That little white line is stretched out DNA. The double helix cork screw spiral can be seen in the lower right image.