“Nano-pillared” surface traps and kills COVID-19

First published 21 September 2020

QUT scientists have developed a way to kill COVID-19 virus on aluminium surfaces with a wet-etching technique that forms random ‘nano-pillars’ like miniscule spears, proven to have both antiviral and antibacterial properties.

  • COVID-19 virus killed on surfaces that have been treated with new technique
  • Extensive lab testing of COVID-19 virus on a wet-etched surface found all virus dead in under six hours
  • COVID-19 virus remains viable on smooth aluminium for more than 24 hours
  • The wet-etching process produces random tiny spears ‘nano-pillars’ on the aluminium alloy used in handrails, door handles that are imperceptible to the touch
  • The nano-pillar surface also kills bacteria.

QUT medical devices specialist Professor Prasad Yarlagadda and virologist Professor Kirsten Spann rapidly began testing the novel coronavirus  SARS-cov-2, which causes COVID-19 disease, on the nano-structured surface, after publishing their findings on its antiviral properties against common viruses earlier this year.

The wet-etching process was tested in a lab by being applied to commercially available aluminium alloy 6063 that is commonly used for doorknobs and frames, window panels and hospital and medical equipment.

Professor Spann said they tested respiratory syncytial virus (RSV) that causes infant bronchiolitis and pneumonia and rhinovirus (cause of the common cold) on the wet-etched aluminium surfaces.

“The nanotextured aluminium surfaces significantly sped up the inactivation process of these two common pathogens,” she said.

“We then collaborated with Dr Alyssa Pyke, together with the Public Health virology team from Queensland Health Forensic and Scientific Services to test the nano-pillared aluminium against SARS-CoV-2 in their  biological secure containment facility that is specially equipped with technology to prevent the virus from spreading.”

Professor Spann said this study is believed to be the first to characterise how virus particles, including those of COVID-19 are influenced by nanostructured surfaces.

“We tested the COVID-19 virus on the surface eight times at each different time points: after 3 hours, 6 hours 24 hours and 48 hours on the nano-pillar surface.

“Within six hours no viable virus could be recovered from the nanostructured aluminium, although the virus remained alive on smooth aluminium for longer than 24 hours and on plastic for longer than two days. 

“At the three-hour mark seven out of the eight tests showed the virus was no longer viable.”

Professor Spann said it was known that ‘flu and respiratory viruses could be transmitted via contaminated surfaces.

“We presume that this is one of the ways that COVID-19 is spreading,” she said.

“We have tested these surfaces against rhinovirus that causes the common cold and so we do know it will work against the common cold. This means these surfaces are highly likely to work against most respiratory viruses and would work outside of a pandemic situation.”

Professor Yarlagadda said wet-etching created random nanopillars using strong etchants (etching solutions) to remove the surface and leave micro-nanostructures.

“The simple wet-etching technique gives surfaces a nanoscale roughness that people cannot feel, but which kills a range of bacteria and viruses,” Professor Yarlagadda said.

“We have tested the nanomechanical properties of the etched surfaces and found the nanopillars can withstand much larger forces than those applied by the hand.

“Since the process involves strong solvents, the etched surfaces have to be installed as end-products rather than treated in-situ.

“As contact transmission can easily occur via hospital medical devices in ICUs, operation theatres or general wards and via general accessible surfaces such as lift buttons, light switches, telephones, handrails, taps, benches, tables, sinks and toilets. All these surfaces could benefit from this technology as an ongoing public health measure.

“At this stage we are working with a bus manufacturing company and one involved in manufacturing hospital beds and trolleys.

“However, we are also working on upscaling this technology to develop a film or spray technology.”

Professor Yarlagadda said the team had also developed another antibacterial technology for use with titanium that can be used for commercial applications to both orthopaedic implants and other surgical equipment.

Antiviral Nanostructured Surfaces Reduce the Viability of SARS-CoV-2 was published in ACS (American Chemical Society) Biomaterials, Science, Engineering.

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