‘Invisible’ Cellulose Coating Protects Against Bacteria

TUESDAY, MAY 23, 2023

A new, thin film made of cellulose fiber that is “invisible to the naked eye,” has been developed to mitigate the transfer of pathogens on high-traffic objects.

According to the release, the material was formulated as a treatment for glass, metal or laminate surfaces to protect against the COVID-19 virus, as well as inhibit the growth of bacteria such as E.Coli.

The coating was reportedly developed by teams from the University of Birmingham, Cambridge University and FiberLean Technologies, led by Professor Zhenyu Jason Zhang from the University of Birmingham School of Chemical Engineering.

About the Coating

Typical chemical disinfectants or antiviral surface materials target structural proteins or nucleic acids. However, the university reports that the researchers focused on drying out the respiratory droplets that contain viruses from capillary forces introduced by the porous structure.

The COVID-19 virus can remain active for several days on surfaces such as plastic and stainless steel, but for only a few hours on materials such as newspaper. To further test this, the team reportedly investigated the structure and performance of the coating made from micro-fibrillated cellulose (MFC) provided by FiberLean.

The porous nature of the film, the university notes, accelerates the evaporation rate of liquid droplets and introduces an imbalanced osmotic pressure across bacteria membrane.

For the research, the team tested whether the coating could inhibit surface transmission of SARS-CoV-2. A three-fold reduction of infectivity was found when droplets containing the virus were left on the coating for 5 minutes. After 10 minutes, the infectivity reportedly fell to zero.

Alternatively, when droplets containing SARS-CoV-2 were left on a glass surface, their initial infectivity was still maintained after 10 minutes.

The antimicrobial tests were repeated with droplets containing bacteria, including E.Coli and S.epidermidis. According to the release, the researchers saw substantial reductions in infectivity at 1 hour and 24 hours.

These experiments were then repeated with aerosolized artificial saliva. The analysis reportedly suggested that the cellulose thin film is also effective in suppressing the contact transfer of respiratory aerosols.

“The risk of surface transmission, as opposed to aerosol transmission, comes from large droplets which remain infective if they land on hard surfaces, where they can be transferred by touch,” commented Zhang.

“This surface coating technology uses sustainable materials and could potentially be used in conjunction with other antimicrobial actives to deliver a long-lasting and slow-release antimicrobial effect.”

Additionally, the researchers then confirmed the stability of the coating by mechanical scraping tests. The coating showed no noticeable damage when dry, according to the university, but was easily removed from the surface when wetted.

The University of Birmingham Enterprise has reportedly filed a joint patent application with FiberLean Technologies and Cambridge University to cover the microfibrillated cellulose, which can inactivate viruses by disrupting the lipid envelop of the virion.

Similar Research

In March last year, a team from the Department of Nano-Bio Convergence of the Korea Institute of Materials Science developed a material that provides antibacterial and antiviral properties without changing the physical properties of various products that are commonly used.

According to the team, while antibacterial films and antibacterial coating products are widely used for elevator buttons, door handles and touch screens, they are difficult to maintain long-term antibacterial durability of the material because of the low transparency and damages caused by frequent use.

The application of antibacterial films and coatings also requires an additional process of attaching or producing a film to an existing product.

Then, in July, a team of researchers made up of Kuman University’s chemistry department faculty and others from the Atal Bihari Vajpayee Indian Institute of Information Technology and Management, Gwalior developed a new anti-viral coating. Using graphene, the paint spray is reported to have anti-viral properties generated from waste plastic.

Capable of killing several viruses, including COVID-19, the anti-viral coating claims to be a first of its kind and is notably cheap to make. Other materials making up the coating include special fatty acids, such as soap, zinc oxide and titanium-oxide-based nanoparticles. The anti-viral coating is also noted to utilize some other unnamed patented components as well.

More recently, earlier this month, the University of Nottingham created a new antimicrobial coating material using a common disinfectant and antiseptic. According to the university's release, the coating effectively kills bacteria and viruses such as MRSA and COVID-19.

In an attempt to prevent infection, the scientists looked at chlorhexidine, which is often used by dentists to treat mouth infections and for pre-surgical cleaning. Instead, they used it to coat the polymer acrylonitrile butadiene styrene (ABS), reportedly finding that the material was effective in killing microbes responsible for a range of infections and illnesses.

This material can be applied on a range of plastic products, which are widely used in medical settings, from hospital beds to intravenous bags. According to the team, microorganisms can survive and remain infectious on abiotic surfaces such as plastic for extended periods, sometimes up to several months.


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