How can materials science contribute to fighting against the new coronavirus?
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OPINION
MATERIAL MATTERS
How can materials science contribute to fighting against the new coronavirus? By Hortense Le Ferrand
V
irus outbreaks are nothing new in history, such as the 1918 flu pandemic and the more recent Zika (2015–2016) and Ebola (2014–2016) outbreaks. But the new coronavirus-induced disease, COVID-19, is dominating the news today, since the World Health Organization (WHO) has declared COVID-19 a pandemic. While biologists and medical researchers are working on a treatment, other scientific areas can also contribute to stopping COVID-19 and caring for patients. For example, the need for medical equipment has urged engineers to use three-dimensional (3D) printing to fabricate reanimation machines, valves, and respiratory aids, demonstrating the potential and benefits of such a technology. Materials science can play a crucial role too.
Characterizing the virus and its modes of action
Developing adequate means for treating viral infection requires prior knowledge
of the microbe structure and mode of action. The entry and infection of a cell by a virus is a multistep process; the first step is the attachment of the virus to receptors at the surface of a cell. What is at the surface of the virus therefore plays a key role in the process. It is known that coronaviruses are round shells of proteins that protect the genetic material, RNA, within. On those shells are exposed spike proteins (S) that contain the receptor-binding site to the cell.1 Recently, the structure of the S-proteins of COVID-19 was revealed using cryogenic electron microscopy (cryo-EM) methods (Figure 1a).2 To realize this, 3207 micrographs were taken and combined into a 3D reconstructed model with a resolution of 0.35 nm. The results show that a stochastic conformation change of the S-protein moves the receptor-binding site to an upward position, making it accessible for binding to
the cell. This information could be used to develop an antiviral drug using a molecule that binds to the receptor or prevents the conformation change. After attachment and entry into a cell, viruses typically release their genetic material, use the cell machinery to replicate it, reassemble their shell around the fresh replicated DNA or RNA, and exit. Blocking any of these steps would prevent the infection, but it has been challenging to image the processes inside the cell once the virus has entered. A study showed that entire cells and their interiors could be imaged in 3D with a resolution of 8 nm.3 To achieve this, a cell was first labeled with fluorescent markers, vitrified by high-pressure freezing to preserve its structure, and imaged by cryogenic light microscopy. This provided a chemical mapping of the cell. The frozen specimen was then mounted onto a cryogenic scanning electron microscope See also stage and milled the MRS Bulletin selectively with December 2019 a focused ion theme on Cryogenic beam to image Electron Microscopy the topography in Materials Science of the interior of the cell. The images gathered from the two microscopic metho
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