The properties of each material, organic or inorganic, depend on how the atoms are arranged on its structure. A wide class of materials we use in everyday life is in crystalline form so their structure is ordered, and their atomic arrangement can be described in great detail. However, very often the materials we encounter crystallize in grains with sizes 10 or 100 times smaller than the diameter of a human hair. This happens, either because this is the only way to synthesize them, or because we made them small, since it is their “nano” size that gives them extraordinary properties. When the crystals are so small the determination of their structure changes from a routine characterization to an extremely challenging problem that requires new science to be solved. The standard way in which we determine the crystal structure is based on observing how a crystal deflects an x-ray radiation impinging on it: the so called diffraction phenomena. If the crystal size falls in the ranges discussed above, the scattering of x-ray radiation is too weak, and a new radiation probe must be found. Our project proposed to use electrons as “the radiation” for investigating the crystal structure instead of x-ray. The electrons interact stronger with matter than x-ray, therefore we have detectable diffraction signals from crystals as small as a few hundreds of nanometers. Furthermore, such an experiment can be done in existing instruments: the transmission electron microscopes. The aim of NanED has been to train a new generation of young electron crystallographers that will spread this novel technique in Europe and beyond and at the same time to develop and apply electron diffraction to any kind of crystalline material, going from inorganic synthetic products to pharmaceutical compounds, from nanoparticles to proteins. The characterization capability of nanocrystals that NanED has set up is going to impact in the society in terms of understanding new material functions and properties. We have been able to understand which are the products of chemical syntheses that were neglected for their polycrystalline yield. We have discovered new polytypes of pharmaceutical compounds that were previously ignored because they were elusive to all the available characterization methods. We demonstrated to be capable of determining the structure of unknown proteins bound to a drug, that up to now were studied in this form since they could only crystallize in nanocrystalline forms and are too small for standard cryo-EM imaging.
