RIO DE JANEIRO, BRAZIL – Researchers from Nanox, a company in São Paulo, sponsored by the Fapesp Innovative Research in Small Businesses Program (PIPE), developed a fabric with silver microparticles on its surface that proved to be capable of deactivating the SARS-CoV-2 coronavirus. In laboratory tests, the material was able to eliminate 99.9 percent of the virus after two minutes of contact.
The material was developed in cooperation with researchers from the Institute of Biomedical Sciences of the University of São Paulo (ICB-USP), the Universitat Jaume I, Spain, and the Center for Development of Functional Materials (CDMF) – one of the Research, Innovation and Dissemination Centers (CEPIDs) sponsored by FAPESP (São Paulo Research Foundation).
“We have already applied for a patent on this technology and have partnerships with two textile mills in Brazil that will use it to manufacture protective masks and hospital garments,” said Luiz Gustavo Pagotto Simões, director of Nanox.
The fabric is made of a blend of polyester and cotton (polycotton) and contains two types of silver microparticles permeating the surface through an immersion process, followed by drying and fixing, called pad-dry-cure.
Nanox was supplying these microparticles which present antibacterial and fungicidal activity preventing the spread of fungus and bacteria that cause bad odors to textile industries and several other segments.
With the emergence of the novel coronavirus and the pandemic in Brazil, the company’s researchers were prompted to assess whether these materials were also able to inactivate SARS-CoV-2, since action against some types of viruses had already been demonstrated in scientific studies.
To perform the trials, the company partnered with researchers from ICB-USP, who were able to isolate and grow the SARS-CoV-2 collected from the first two Brazilian patients diagnosed with the disease at the Albert Einstein Hospital.
Fabric samples with and without silver microparticles incorporated in its surface were identified by researchers from Universitat Jaume I and CDMF by spectroscopy and placed in tubes containing a solution with large quantities of SARS-CoV-2, grown in cells.
The samples were kept in direct contact with the viruses at different time intervals of two and five minutes to assess the antiviral activity. This was a blind test, conducted twice, on two different days and by two different groups of researchers.
The results of the PCR analysis of viral genetic material quantification showed that tissue samples with different silver microparticles incorporated in the surface inactivated 99.9 percent of copies of the novel coronavirus present in the cells after two to five minutes of contact.
“The amount of virus we placed in the tubes in contact with the fabric is much higher than what a protective mask is exposed to, and yet the material was able to eliminate the virus with such efficacy,” says Lucio Freitas Junior, researcher at the ICB-USP Level 3 (NB3) Biosafety Laboratory.
“It’s as if a protective mask made from the fabric were to be drenched with particles containing the virus,” the researcher compared. In addition to testing for antiviral, antimicrobial and fungicidal activity, the material also underwent testing for allergic, photo-irritant and photosensitive potential to remove the risk of causing dermatological conditions.
Application
The company now intends to assess the length of the microparticles’ antiviral action on the fabric. In tests related to the bactericidal properties, the materials were able to control fungi and bacteria in fabrics even after 30 washes, says Simões.
“Since the material has this bactericidal property even after 30 washes, it is likely to retain antiviral activity for that same time,” he estimates.
According to the researcher, microparticles can be applied to any fabric made up of a blend of natural and synthetic fibers. In addition to fabrics, the company is now testing the ability to inactivate the novel coronavirus through silver microparticles incorporated into the surface of other materials, such as plastic films and a flexible rubber-like polymer, which it used to develop a protective mask against the novel coronavirus in partnership with toy manufacturer Elka.
“The fabric was the first result from the application of silver microparticles to inactivate the novel coronavirus. But soon we should have several others,” says Simões.