The first direct images of the DNA double helix have been taken using electron microscopy.

In a study published in the journal NanoLetters, Enzo di Fabrizio, head of the Nanostructures Department at the University of Genoa, and his team managed to take a picture of the structure which had previously only been observed indirectly using X-ray crystallography.

The fragile nature of DNA means that electron energy can destroy single strands so the helix could only be observed using DNA "cords" -- tiny ropes of genetic material consisting of several intertwined strands. Using a custom-built base of nanopillars this DNA cord was stretched out ready to be picked out by the electron beams. "With improved sample preparation and better imaging resolution, we could directly observe DNA at the level of single bases," said Di Fabrizio according to New Scientist.

The ability to take direct images of DNA means that detailed information which it was impossible to obtain using diffraction (X-ray crystallography relies on mathematical interpretation of diffraction patterns for its information) could soon be available for study. Genetic researchers will also be able to use the technique to observe how DNA interacts with other substances.