A special self-adhesive plastic film to protect the surface (such as door handles, handrails, elevator buttons and touchscreens) can inactivate the film new coronavirus per contact.
The material introduced by the Promaflex industry contains silver and silica microparticles developed by the São Paulo company Nanox and supported by the Fapesp Innovative Research in Small Business Program (PIPE).
Tests carried out in the Level 3 Biosafety Laboratory of the Institute of Biomedical Sciences of the University of São Paulo (ICB-USP) showed that the polyethylene-based material can subsequently remove 99.84% of Sars-CoV-2 particles two minutes of contact.
“The technical standard for measuring antiviral activity on plastics and other non-porous surfaces, ISO 21702, specifies that the material must demonstrate this effect within four hours. The plastic film with the additive was able to achieve the goal in a much shorter time, ”Lucio Freitas Junior, researcher at ICB-USP, told Agência Fapesp.
It is not easy to test the virucidal effect of plastic films. The material samples with and without silver and silicon dioxide microparticles were kept in direct contact with Sars-CoV-2 at various time intervals.
After the specified periods of time, the coronaviruses present in the material samples were collected and brought into contact with the so-called Vero cells – cell lines that are commonly used in microbiological cultures and were synthesized from cells isolated from the kidneys of a species of monkey. This is used to assess the ability to infect and multiply after exposure to plastic films. The results showed an almost 100% reduction in copies of Sars-CoV-2 that came in contact with samples of the adhesive film in which the silver and silicon dioxide microparticles were incorporated after two minutes of exposure.
“Since silver and silica microparticles are added to the plastic compound during manufacture, the antimicrobial effect is retained throughout the life of the material,” says Luiz Gustavo Pagotto Simões, Director of Nanox. However, the manufacturer recommends using the material for up to three months to avoid wearing the material due to excessive contact.
And the antiviral mask?
The adhesive film is the second plastic material with silver and silica microparticles sold by Nanox to protect against the market entry of Covid-19. In cooperation with the toy manufacturer Elka, the company in São Paulo developed a reusable mask made of a flexible plastic (thermoplastic) and the additive applied to the surface, which promises better protection against the new coronavirus.
In early August, the National Health Surveillance Agency (Anvisa) registered the product as a PFF2 mask, which allowed it to be used as personal protective equipment (PPE).
Silver and silica microparticles have also been applied to the surface of fabrics to develop anti-coronavirus clothing. In laboratory tests, the material with the Sars-CoV-2 additive was able to inactivate it even after two minutes of contact.
The additive has been used in clothing and fabrics made by companies such as Santista, the Malwee Group and Cedro Têxtil, among others. “The suitcase bothered us. We changed our business model a little and, in addition to selling the additive, we also signed license agreements for the use of the brand, ”said Simões.
In this case, the material will peel off when the fabric is washed, as it is a cover. “But we did tests on fabrics that had been excessively laundered and we found there was no loss of effectiveness,” said Freitas Junior.
* This content was originally created by Agência Fapesp.