Researchers at Nanox, a São Paulo-based company supported by FAPESP’s Innovative Research in Small Business Program (PIPE), have developed a fabric containing antimicrobial silver nanoparticles that has proved capable of inactivating the novel coronavirus SARS-CoV-2.
The material eliminated 99.9% of the viral load in a laboratory inoculum container after two minutes of contact.
The material was developed with the collaboration of researchers at Spain’s Jaume I University as well as two Brazilian institutions: the University of São Paulo’s Biomedical Sciences Institute (ICB-USP) and the Center for Research and Development of Functional Materials (CDMF), a Research, Innovation and Dissemination Center (RIDC) supported by FAPESP and hosted by the Federal University of São Carlos (UFSCar) in the state of São Paulo.
“We’ve applied for a patent on the technology, and we’re partnering with two textile companies in Brazil that will use it to produce PPE such as face masks, hospital gowns and coveralls,” Nanox CEO Luiz Gustavo Pagotto Simões told Agência FAPESP.
The fabric is a blend of polyester and cotton called polycotton and is coated using the pad-dry-cure with antimicrobial products created by Nanox containing two kinds of silver nanoparticles. Padding is a coating technique commonly used as a textile finishing method.
Nanox has been supplying nanoparticles for some time to textile companies and various other industries for their antiviral, antibacterial and fungicidal properties, as demonstrated in a number of scientific papers (read more at: agencia.fapesp.br/30191). With the advent of the COVID-19 pandemic, the researchers decided to investigate whether the product could inactivate SARS-CoV-2.
To perform the tests, the firm contacted researchers at ICB-USP who produced the virus in their laboratory after it was isolated from the first two patients diagnosed with the disease at the Albert Einstein Jewish Hospital (HIAE) in São Paulo City (read more at: agencia.fapesp.br/32699).
Samples of fabric with and without silver nanoparticles were characterized by researchers at Jaume I University and CDMF using Raman spectroscopy. Test specimens were placed in tubes containing a solution with large amounts of cell-cultured SARS-CoV-2. The specimens were kept in direct contact with the viruses for periods of two and five minutes, and antiviral activity was measured. The experiment was performed twice on different days by two different groups of researchers to ensure that the results were analyzed blindly.
The viral genetic material was quantified using real-time PCR, and the ability of each sample to inactivate SARS-CoV-2 was determined. The findings showed that the fabric containing silver nanoparticles inactivated 99.9% of the viruses after two and five minutes of contact. “The quantity of viruses placed in the tubes with pieces of the fabric was far greater than the viral load to which a face mask is exposed, and even so the material eliminated the viruses with efficacy,” said Lucio Freitas Junior, a researcher in ICB-USP’s Biosafety Level III laboratory. “It was as if a face mask made with the fabric had been soaked in a bucket of particles containing the virus.”
In addition to tests to evaluate antiviral, antibacterial and antifungal activity, the material was also tested for allergic, photoirritant and photosensitive potential to ensure that it did not cause skin irritation.
The new technology was described in the article “Ag nanoparticles-based antimicrobial polycotton fabrics to prevent the transmission and spread of SARS-CoV-2,” published on its preprint version (not yet reviewed) in the platform BioRxiv (*).
Application to other materials
Nanox plans to determine how long the antiviral effect of the nanoparticles lasts in the fabric. Testing of their bactericidal capacity showed that they could control fungi and bacteria even after the fabric was washed 30 times. “Given this capacity to maintain antibacterial activity even after 30 washings, the material probably also maintains antiviral activity for the same amount of time,” Simões said.
The nanoparticles can be applied to any fabric that is a blend of natural and synthetic fibers, he added. The firm is now testing their capacity to inactivate SARS-CoV-2 in other materials, such as plastic film and a rubber-like flexible polymer used to develop a face mask for protection against the virus in partnership with plastic toy maker Elka (read more at: agencia.fapesp.br/33085).
“The fabric application of these silver nanoparticles to inactivate the coronavirus is the first result, and we’ll soon have several others,” Simões said.
