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In a new study available on the preprint server Pre-prints *, researchers have innovated a transparent face shield with inherent antimicrobial activity that serves two purposes – additional protection against microbial infections and reduced generation of infectious waste.
Study: Antimicrobial face shield: new generation of facial protective equipment against SARS-CoV-2 and multidrug resistant bacteria. Image Credit: Kamil Macniak / Shutterstock
introduction
The team observes that if the facial protective equipment is transparent and physically protects against microbial infections, it can be contaminated and be a source of infection. People who are infected can continue to spread the infection despite wearing protective equipment, as it does not inactivate the microbial load transferred to it when breathing, sneezing or coughing. Once infected, it constitutes a growing source of biological waste – an environmental risk associated with the management of waste from this protective equipment.
In the present study, the researchers manufactured the next generation of facial protective equipment – composed of an antimicrobial coating of benzalkonium chloride (BAK) on polyethylene terephthalate (PET). This single-use, transparent antimicrobial face mask inactivates enveloped viruses, such as Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) within a minute of contact and resistant to methicillin Staphylococcus aureus (SARM) and Staphylococcus epidermidis (MRSE).
SARS-CoV-2 has been shown to be transmitted through surfaces of contaminated materials, in addition to aerosol transmission. Infectious microorganisms such as the influenza virus and S. pneumoniae are significant global risks of death from respiratory infection. Face shields are one of the protective equipment choices that form a physical barrier between the wearer and these biological agents, thereby preventing the agent from entering through the respiratory tract and mucous membranes.
A pre-printed version of the study is available on the website Pre-prints* server while the article is subject to peer review.
Antimicrobial coating preparation and testing
Facial protection equipment is typically made using PET, a low-cost, transparent, recyclable commercial polyester. PET does not have antimicrobial activity.
The researchers used a quaternary ammonium compound, such as benzalkonium chloride (BAK), to impart antimicrobial activity to the face shield. BAK is reported to inactivate enveloped RNA viruses and multi-resistant Gram-positive bacteria. The PET sheets were dipped 70% ethyl alcohol with 0.1% w / w BAK for 1 min at 25 ° C. This was followed by drying at 60 ° C for 48 h and sterilization under UV radiation for 1 hour.
Researchers demonstrated the antimicrobial properties of the BAK coating using atomic force microscopy and scanning field emission electron microscopy with elemental analysis and confirmed its opacity.
Antimicrobial activity against viruses and bacteria
During this ongoing COVID-19 pandemic, severe pneumonia, caused by bacteria such as Streptococcus pneumoniae, is associated with SARS-CoV-2 infection. These bacterial infections are increasingly resistant to antibiotics and increase the risk of death from coinfection.
The researchers studied the antibacterial activity of the disks made against phage Phi 6 (DSM 21518) and SARS-CoV-2, and MRSA, COL and MRSE, RP62A by agar disk diffusion assays. They observed potent antiviral and antibacterial activity.
They also tested the antimicrobial durability of the BAK coating when washed in water. Because BAK is highly soluble in water, the BAK coating is easily washed off. As a result, the surface loses its antimicrobial activity, making the face shield a single use facial protective equipment.
It is important to note that the offered PET plastic can be recycled and reused – the BAK coating can be easily applied to the surface of the PET. The application of this ensures a reduction in the production of waste caused by the increased use of such protection systems.
The mechanism of antimicrobial action
The positively charged nitrogen atoms in BAK damage the bacterial surface or disrupt the phospholipid bilayer membrane, glycoprotein envelope, and spike glycoproteins of viruses such as phi6, SARS-CoV-2, and IFV. However, BAK is a Food and Drug Administration (FDA) approved product used in disinfection applications such as additives in soaps and hand sanitizers; thus, it is safe to use.
Conclusion
This work demonstrated a fabricated transparent face shield capable of providing additional protection by acting as a physical barrier with inherent antimicrobial activity against enveloped viruses such as SARS-CoV-2 and multidrug resistant bacteria. This is a single use antimicrobial face shield made by an inexpensive procedure of dip coating polyethylene terephthalate with benzalkonium chloride.
Figure 7. Applications of transparent polyethylene terephthalate coating technology with benzalkonium chloride antimicrobial coating for the next generation of facial protective equipment: face shields, plastic masks, helmets, goggles, helmets and separation screens space
In particular, this antimicrobial material is recyclable, and it reduces the generation of infectious biological waste. It can be used for other protective gear such as goggles, helmets, plastic masks, space separation meters or vehicle screens to protect against ongoing viral infections and future variants. Researchers say this low-cost technology would be very useful in tackling the current COVID-19 pandemic and protecting healthcare workers from multidrug-resistant infections in developed and underdeveloped countries.
*Important Notice
Pre-prints publishes preliminary scientific reports which are not peer reviewed and, therefore, should not be considered conclusive, guide clinical practice / health-related behavior, or treated as established information.
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