Startup battles virus speading
Viruses are ubiquitous in our lives. Especially now in winter we easily get sick due to the high virus load, largely from so-called aerosols. These are virus-laden solid or solid/liquid particles that travel in the air. A precise understanding of virus aerosols is essential in order to identify the transmission mechanisms of viruses, such as SARS-CoV-2 or influenza, and to develop solutions for prevention. The physics and chemistry of virus aerosols are investigated at CIC nanoGUNE in the Basque technology network BRTA. Research requires virus models that are as detailed, small and precise as possible. NanoGUNE works with nanoscale molecular aggregates, but increasingly uses water / virus models on the centimeter scale to complement wetting and dewetting studies on the nanoscale.
Figure 1 shows the model of an influenza virus with a diameter of ca. 120 nm. Its surface consists of up to 500 so-called "spikes", which - unlike on CoV - are only about 10 nm apart, such that tiny capillaries are located between the spikes. Liquid aerosols lose water very quickly in air, they quasi dry up, which, on the one hand, can deactivate viruses. On the other hand, the loss of mass means a longer residence time in the air. This fine balance determines the transmission. Do the capillaries play any role?
Figure 1: Model of an influenza virus, dry and with an ultrathin layer of water (Source: Reddy et al., Structure 23 (2015) 584)
For the centimeter-sized model, the capillaries must be less than 1 mm in size, otherwise gravity will falsify the result. Such precision cannot be achieved for microparts with conventional 3D printing processes, such as BJ or SLM. With this problem, nanoGUNE contacted MetShape, who offer top precision and resolution for complex components.
As a 3D printing service provider, MetShape specializes in complex problems and metallic micro-precision parts, enabling to support this research project with its innovative technology, by printing a high-precision virus model on the scale 250000:1. This means that the model has a diameter of approximately 30 mm. Thanks to its expertise in precise indirect additive manufacturing processes, MetShape was able to print, debind and sinter the model, and provide a finished model to nanoGUNE. No post-processing steps for the virus model were required, as MetShape's technology achieves excellent surface quality without the requirement of support structures.
Compared to a standard polymer model (see Figure 2), the metal model performs significantly better due to the lower mass of the water, based on the smaller size of the model. Both models were hydrophilized with an adhesive spray. In the case of the polymer model, however, the resulting large water mass causes droplet artefacts, while the metal model is correctly wetted.
Figure 2: Comparison of water geometry on polymer and metal models
NanoGUNE is enthusiastic about the result of the 3D printing service provider: “Thanks to the model printed by MetShape, we can now carry out our experiments on the wetting and dewetting of water on viruses and thus achieve a new milestone in the research of virus aerosols. With the new possibilities through innovative manufacturing technologies, we are taking a big step closer to our long-term goal of protecting as many people as possible from virus infections.” (Ikerbasque Prof. Alexander Bittner). The next generation of air condition technologies will undoubtedly require advances in controlling the spread of aerosols.
Figure 3: Model of an influenza virus printed by MetShape, scale 250000:1
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