Researchers have developed a silicon surface covered with nanoscale spikes that can effectively pierce and destroy a common virus that causes respiratory diseases, especially in infants and young children, with an efficiency of up to 96%. This technology can be used to protect researchers, medical workers and patients from the spread of the virus.
Among the four strains of human parainfluenza virus (HPIV), HPIV-3 is the most virulent and can cause bronchitis, tracheitis or pneumonia in infants and young children. Seasonal outbreaks of HPIV-3 infection occur every year, and the virus is spread through the air or direct or indirect contact with contaminated surfaces.
There are currently no vaccines or antiviral drugs to prevent or treat HPIV-3 infection, so maintaining general hygiene and surface hygiene becomes a top priority. Now, researchers from the University of Rovira e Vergeli (URV) in Spain and the Royal Melbourne Institute of Technology (RMIT University) in Australia have collaborated to develop a spiked silicon surface with surprising virus-killing properties.
Inspired by dragonfly wings, researchers at RMIT University have demonstrated the efficacy of "mechanically sterilizing" nanoscale spikes made of titanium to kill antibiotic superbugs on their surfaces. Likewise, Pauling was familiar with insects with antibacterial wings. "Insects such as dragonflies or cicadas have wings with nanostructures that can pierce bacteria and fungi," he said.
But viruses are different. They are smaller than bacteria, so the nanonails used to kill them need to be smaller as well. Although the antiviral properties of heavy metals and their derivatives have been intensively studied, viruses are thought to be inactivated due to the release of metal ions and the generation of reactive oxygen species that damage membranes and proteins. Therefore, in the current study, the researchers chose to use boron-doped silicon wafers.
Vladimir Paulin, one of the corresponding authors of the study, said: "In this case, we used silicon because it is technically less complex than other metals."
To create the sharp surfaces, they used plasma reactive ion etching, a process that uses a chemically reactive plasma to remove material deposited on the wafer, allowing the researchers to fine-tune the height and spacing of the nanoscale spikes. The resulting surface is covered with 2-nanometer-thick spikes—30,000 of them could fit into a human hair—and is only 290 nanometers high. The diameter of HPIV-3 viral particles ranges from 100 nanometers to 420 nanometers.
Surfaces incubated with HPIV-3 for 1, 3, and 6 hours were examined under a scanning electron microscope (SEM), showing that the virus particles retained their usual shape after 6 hours of incubation on silicon surfaces without added spikes. However, on the spiked surface, the shape of the HPIV-3 particles was affected; after 1 and 3 hours of incubation, the sharp tips of the spikes penetrated the particles and deformed them. After six hours, the pellets become deflated. At each time point, there was a significant decrease in infectious virus particles on the nanonail silicone surface: 74% after one hour, 85% after three hours, and 96% after six hours.
When tested on bacteria, the researchers found that the nanospikes were lethal to them, too. They were able to destroy cells of two common bacteria associated with hospital infections, Pseudomonas aeruginosa and Staphylococcus aureus ("Staphylococcus aureus"), although not as effectively as HPIV-3. After 18 hours of incubation, the proportion of nonviable Pseudomonas aeruginosa and Staphylococcus aureus was found to be 15% and 25% respectively.
The findings demonstrate the effectiveness of using silicon nanonails as virucidal agents. The researchers anticipate that this technology will be used in laboratories and medical centers where potentially hazardous biological materials are stored, making these environments safer for researchers, medical workers, and patients.
The research was published in the journal ACSNano.