Researchers have developed a silicon surface covered in nanosized spikes that is 96% effective in impaling and destroying a common virus responsible for causing respiratory illnesses, particularly in infants and young children. The technology could be used to safeguard researchers, health workers and patients from viral spread.
Of the four strains of human parainfluenza viruses (HPIVs), HPIV-3 is the most virulent and can lead to bronchiolitis, bronchitis, or pneumonia in infants and young children. Yearly, seasonal outbreaks of HPIV-3 infections are common, with the virus spread via airborne transmission or direct and indirect contact with contaminated surfaces.
No vaccines or antivirals are currently available to prevent or treat HPIV-3 infections, making maintaining general and surface hygiene a priority. Now, researchers from the Universitat Rovira i Virgili (URV) in Spain and Australia’s RMIT University have collaborated to develop a spiked silicon surface with impressive virus-killing properties.
Inspired by dragonfly wings, RMIT researchers have already demonstrated the efficacy of using a nanoscale spiked ‘mechano-biocidal’ surface made of titanium to impale and kill antibiotic-resistant superbugs. Likewise, Baulin is familiar with insects possessing antimicrobial wings.
“The wings of insects such as dragonflies or cicadas have a nanometric structure that can pierce bacteria and fungi,” he said.
Viruses are different, though. They’re smaller than bacteria, so the nanospikes designed to kill them need to be smaller, too. While heavy metals and their derivatives have been intensively studied for their antiviral properties, the viruses are thought to be inactivated due to metal ion release and the production of reactive oxygen species that can damage membranes and proteins. So, for the current study, the researchers opted to use a boron-doped silicon wafer.
“In this case, we used silicon because it is less complicated technically speaking than other metals,” said Vladimir Baulin, one of the study’s corresponding authors.
To create their sharp surface, they used plasma reactive ion etching, a process that uses chemically reactive plasma to remove material deposited on wafers and enabled the researchers to fine-tune the nanospikes’ height and spacing. The resulting surface is full of spikes 2 nm thick – 30,000 of them would fit in a human hair – and 290 nm high. HPIV-3 viral particles have a diameter ranging between 100 and 420 nm.
Surfaces incubated with HPIV-3 for one, three, and six hours were examined under scanning electron microscopy (SEM) and showed that, after six hours on non-spiked silicon surfaces, the viral particles retained their usual shape. However, the shape of HPIV-3 particles on the spiked surfaces was compromised; the sharp tips of the spikes penetrated and deformed them one and three hours after incubation. At six hours, the particles were deflated. At each time point, there was a significant decline in infectious viral particles on the nanospike silicon surface: a 74% drop at one hour, 85% at three hours, and, after six hours, a 96% drop.
When tested on bacteria, the researchers found the nanospikes were also deadly to them. They disrupted the cells of two bacteria commonly associated with hospital-acquired infections, Pseudomonas aeruginosa and Staphylococcus aureus (‘golden staph’), although the effect was not as great as that seen with HPIV-3. After 18 hours of incubation, the proportion of non-viable P. aeruginosa and S. aureus was found to be 15% and 25%, respectively.
The study’s findings demonstrate the effectiveness of using silicon nanospikes as a virucidal. The researchers foresee the technology being applied in labs and health centers where potentially dangerous biological materials are housed, making these environments safer for researchers, health workers and patients.
The study was published in the journal ACS Nano.
Source: URV
