Individual protein molecules imaged on graphene

New Scientist : To take pictures of molecules like proteins, current imaging methods such as x-ray crystallography and cryo-electron microscopy require averaging millions of individual images. The reason is that, during the process, the molecules can move around or become damaged. An alternative technique that doesn’t damage the molecules, known as electron holographic microscopy, has not proven useful until now because the substrate on which the molecules were placed was too thick for the low-energy electron imaging beam to pass through. Now Jean-Nicolas Longchamp of the University of Zurich, Switzerland, and his colleagues have found a substrate that is thin enough—single layers of graphene. Using this technique, they isolated individual molecules of a variety of proteins such as hemoglobin and took pictures of them, all of which closely matched images of similar molecules produced by other methods. Longchamp says that the next step will be to take pictures of molecules that can’t be imaged with existing techniques.