Visualization of artificial proteins with cryo-electron microscopy
In 2017, the Nobel Prize in Chemistry was awarded to Jacques Dubochet, Joachim Franck and Richard Henderson in recognition of their work on the development of cryo-electron microscopy (see IIR news 0022596).
Traditional optical microscopes use visible light to observe samples. Electron microscopes use a beam of accelerated electrons as a source of illumination. This allows a more precise and greater magnification of the object observed, thanks to electromagnetic lenses. The disadvantage of this technique is that the samples must be dehydrated, colored, or exposed to X-rays. These techniques alter the sample and therefore do not allow it to be observed in its natural state. With cryo-electron microscopy, the sample is cooled to overcome this problem. To prevent the sample from freezing, vitrification is used. Cryo-electron microscopy has been developed since the 1980s, but this technique has recently been coupled with work on 3D imaging and has also made it possible to identify the Zika virus. This is why cryo-electron microscopy was only recently awarded the Nobel Prize in Chemistry.
A new application for cryo-electron microscopy
Researchers at the University of Berkeley recently used cryo-electron microscopy to study synthetic proteins: peptoids. It is the first time that atomic changes have been observed in soft synthetic materials. Unlike proteins (which until now were the most easily observed molecules thanks to cryo-electron microscopy), peptoids have a messy atomic structure, which makes their observation usually difficult. With cryo-electron microscopy, researchers could make it easier to design and synthesize this type of material on an atomic scale. The results of these studies could contribute to design a variety of nanomaterials such as flexible nanosheets, and could advance at a low cost a number of applications such as synthetic, disease-specific antibodies and self-repairing membranes or tissue.
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