Quantitative study of nanofabricated surfaces could help limit food-borne virus spread

Ever year, more than half of foodborne illnesses are caused by viruses. In the hopes of reducing the spread of such viruses, researchers have been studying how they adhere and spread on surfaces. For the first time, researchers have developed a method of qualitatively studying how well viruses stick to surfaces.

“Since foodborne illness outbreaks can significantly compromise social events and public health, there is an urgent need to develop materials that reduce microbial adhesion,” said Rong Wang.

Guo et al. studied the effect of nanofabrication of a material’s surface on virus adhesion using male-specific coliphage, or MS2, which is often used as a surrogate for foodborne viruses in the lab. The virus was added to silicon wafers etched with nanoholes 50 nanometers wide and 100 nanometers apart. Using scanning electron microscopy and atomic force microscopy, the researchers were able to effectively evaluate virus adhesion by counting the virus density and measuring the strength of virus adhesion against the test surfaces.

They found the nanoholes helped reduce the number of viruses that were able to stick to the surface in comparison to smooth silicon surfaces. They additionally found the nanoholes lessened the strength of the viruses’ adhesion to the surface by half.

The researchers hypothesized this was due to a special effect known as the Cassie-Baxter state. While a porous surface offers more surface area, the available contact area for viruses was reduced, and the viruses were unable to enter the holes. This was due to the free energy of a droplet on the nanostructured surface, which causes a suspension of liquid at the surface of the nanohole, barring the virus from entering.

Source: “Nanofabrication of silicon surfaces for reduced virus adhesion,” by Ao Guo, Y. Carol Shieh, Ralu Divan, and Rong R. Wang, JVST: B (2020). The article can be accessed at https://doi.org/10.1116/6.0000548 .