Antiviral Surfaces
The Covid pandemic highlighted the importance of keeping surfaces clean. But this was far from news for hospitals and other sensitive areas struggling to control the spread of infections.
Regular cleaning with disinfectants is the accepted practice to control this risk.
Tentatives have been made to make door handles and other surfaces in copper to leverage the metal”s antibacterial activities. Copper door handles showed an average of 59% reduction, while copper handrails showed an average of 33% reduction.
However, metal-based biocide surfaces can be toxic to human cells and the environment, very expensive, and prone to corrosion.
In the context of rising antibiotic resistance, finding new ways to kill bacteria that are not based on chemicals is a growing concern.
Source: Antibiotics
This is also more complex for viruses, which are much smaller and less sensitive to metal ions than bacteria. Since viruses are responsible for most airborne infections, another solution is needed, ideally with a much higher efficiency rate at killing viruses.
One such solution might come from nanotechnology, which involves adapting silicon wafers normally used in semiconductor manufacturing into an antiviral surface.
Silicon Nanospikes To Stab Viruses
Researchers in Australia (University of Melbourne, RMIT University, Monash University, and Swinburne University of Technology) University Rovira I Virgili in Spain, KAITEKI Institute in Japan, and CSIRO Manufacturing (Commonwealth Scientific and Industrial Research Organisation) have teamed up to create a new type of silicon surface.
By bombarding a smooth silicon wafer with ions, they strategically removed some of the material. This left behind a series of nanospikes 2 nm thick and 290nm tall.
Source: RMIT University
The idea was inspired by biological spikes on the wings of insects like dragonflies, which are able to pierce the cells of bacteria and fungi, helping to control diseases previously studied by the RMIT team.
But for viruses, much smaller than bacteria, even smaller types of spikes than the biological ones were needed.
This is where the Spanish researchers entered, creating a computer simulation of the interactions between the viruses and the spikes before testing it in collaboration with the other researchers.
Source: ACS Publication
The test virus was Human parainfluenza virus hPIV-3, the most virulent serotype, causing bronchitis, pneumonia, and croup.
By using electron microscopy they noticed that the silicon spikes could perforate the virus particles, and destroy them in a few hours. In total, 96% of the viruses were either ripped apart or damaged to the point where they could no longer replicate to cause infection.
Source: RMIT University
The Next Step For Antiviral Nanospikes
The researchers found that while mostly focused on viruses, the spike could also affect bacteria.
For example, P. aeruginosa, a key bacteria in airborne infection, especially of immunocompromised patients and in hospitals, saw 15% of the cells becoming nonviable after 18 hours. The results were even better with a 35% death rate in S. aureus, an often antibiotic-resistant bacteria responsible for many dangerous and hard-to-treat infections in hospitals.
Observation with an electronic microscope confirmed that the bacteria were getting perforated by the silicon nanospikes.
Source: ACS Publication
The researchers found that a smaller gap between the spikes induces more mechanical stress on the virus, likely increasing the efficiency.
They will now investigate variations of the silicon nanostructures and different materials, as well as different viruses, in order to find the most effective, broad-spectrum antiviral surfaces.
And potentially, a surface that can work efficiently both as an antiviral and antibacterial would be ideal.
Antiviral Surfaces Companies
1. Bio-Gate (BIG1.DE)
Bio-Gate specializes in hygiene products, including antiviral and antibacterial coatings. This includes HyProtect, made of silver and polysiloxane, and MicroSilver, made of a microporous silver additive.
These products can be added to textiles, polymers, mattress foams, as a spray, or as a lacquer/varnish. In the last few years, the company has also partnered with implant manufacturer to add Hydroprotect to their medical implants.
For now, the company is mostly focused on silver-based biocide products but would be equally branching out into innovative nanostructures like the silicon nanospikes discussed in this article.
2. Polygiene (POLYG)
Polygiene is a company that specializes in antibacterial and anti-odor treatment, especially for textiles. It also has an antiviral treatment, Polygiene ViralOff, based on silver chloride, the same way its anti-odor solution Polygiene StayFresh works.
It also uses silica particles for its Polygiene OdorCrunch product, plant-based substances for its Polygiene StayFreshBIO, and polymers for Polygiene ShedGuard.
The Swedish company is mostly selling in Europe and the Asia Pacific region, with the sport & outdoor + industry segments making up half of the revenues.
Source: Polygiene
The company is expanding its offering. In early 2024 it added LEXAN and CLINIWALL sheets for clean surfaces, interior, and wall cladding. These sheets have a high dirt-repellent effect and are used in hospitals and public facilities.
The group also expects to enter the automotive segment later this year.
The expanding number of active sectors, the recent entry into healthcare, and the diversity of materials already used for their biocide effects indicate that the company could be among the industry actors to adopt innovative solutions like silicon nanospikes when that technology matures.