An international team of scientists has recently demonstrated that zinc-embedded polyamine fibers can effectively absorb and inactivate human respiratory viruses, including influenza A virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Thus, a face mask or other personal protective equipment (PPE) made from this fiber is expected to provide better protection against viral transmission. The study is currently available on the bioRxiv* preprint server.
Since the emergence of coronavirus disease 2019 (COVID-19) pandemic in late December 2019, the highly infectious SARS-CoV-2 virus has infected nearly 48 million people and claimed more than 1.22 million lives globally. Until the development of specific therapeutics or vaccines, proper implementation of non-pharmacological measures, such as wearing face masks or the use of other PPE, frequently washing/sanitizing hands, and movement restrictions, are believed to be the best possible way to contain the spread of SARS-CoV-2.
Although face masks can protect the respiratory system from direct viral infection, viruses can remain active for hours on the PPE surface. In such circumstances, there is always a risk of further viral transmission if the PPE/face mask is not discarded appropriately after use.
In the current study, the scientists aimed to construct a special type of zinc-embedded fabric and determine its efficacy in absorbing and inactivating human respiratory viruses, such as influenza A virus and SARS-CoV-2. Several studies have shown that metals, such as copper and zinc, are effective in inactivating viruses. This is most likely because of metal ions' ability to trigger RNA hydrolysis, membrane disruption, or viral protein degradation.
Absorption and release of IAV and SARS-CoV-2 from fabrics. A) Photographs of cotton control, PA66 and polypropylene fabric samples. B) Schematic of the experimental procedure for exposing and isolating RNA virus from fabrics. C) Analysis of virus medium retention by fabrics per volume of input medium. Values were obtained by weighing each fabric before and after the addition of virus medium, and after removal of the virus medium. D) Analysis of virus medium retention by fabrics normalized by dry weight of each fabric. Values were obtained by weighing each fabric before and after the addition of virus medium, and after removal of the virus medium. E) Plaque assay of IAV present in virus medium after removal of the medium from each fabric. F) Quantitation of the amount of virus remaining on each fabric, normalized by the dry weight of each fabric. G) Effect of different tween-80 concentrations on IAV plaque assay read-out. H) Effect of 0.05% tween-80 in PBS on the amount of virus released from each fabric. I) Quantitation of IAV titers after absorption of the virus to the fabrics and washing of the fabrics with PBS or PBS containing different concentrations of tween-80. J) Quantitation of SARS-CoV-2 titers after absorption of the virus to the fabrics and washing of the fabrics with PBS or PBS containing different concentrations of tween-80. Error bars indicate standard deviation. Asterisk indicates pvalue, with * p<0.05, ** p<0.005, and ns p>0.05.
Current study design
The scientists tested the virus-absorbing ability of different fabrics, including cotton, polyamide 66, and polypropylene. Also, they checked whether zinc ions embedded in the fabrics are capable of inactivating viruses.
The ability of fabrics to absorb viruses depends on many factors, such as hydrophobicity, breathability, and electrostaticity. To determine the correlation between moisture retention and virus absorption abilities of fabrics, the scientists sequentially applied liquid samples containing influenza A virus and SARS-CoV-2 to cotton, polyamide 66, and polypropylene. After 30 minutes of incubation, they checked the liquid retention and virus absorption ability of the fabrics. According to the study findings, cotton and polyamide fabrics retained more liquid and absorbed more viruses than the polypropylene fabric. However, in terms of removing the virus from the fabrics, cotton was found to be less favorable than polyamide fabrics. This indicates that face masks or PPE prepared from cotton or polyamide would be more effective in trapping respiratory viruses.
As an embedding metal, they chose zinc over copper because of the relatively higher zinc tendency to be ionized. This makes zinc rapidly available for reaction. For further experiments, they embedded zinc oxide in the polyamide 66 polymer and checked its ability to inactivate the influenza A virus and SARS-CoV-2. According to the study findings, zinc ions significantly reduced the viral titer by destabilizing viral surface proteins, such as hemagglutinin and spike protein. Furthermore, they observed that the maximum reduction in viral titer occurred between 30 seconds and 5 minutes of viral incubation with zinc-embedded polyamide fabric.
Notably, the scientists observed that the zinc-embedded polyamide fabric can effectively inactivate a wide range of viral loads and that the inactivation rate can beat the amount of infectious virus expelled by a cough.
The study significance
The study findings indicate that face masks or other PPE prepared from zinc-embedded polyamide fibers can provide better protection against highly infectious respiratory viruses, such as SARS-CoV-2 and influenza A virus. The study also suggests that cotton masks with higher virus-absorbing and lower virus-releasing abilities may actually increase the risk of viral infection if reused without proper washing. Similarly, polypropylene-based masks with lower virus absorption ability may accelerate viral transmission.
bioRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.