Cellulose coating inactivates SARS-CoV-2 virus within minutes

Recent research has demonstrated the remarkable capabilities of a thin cellulose film in deactivating the SARS-CoV-2 virus rapidly, preventing bacterial growth, and reducing pathogen transfer through contact. Developed collaboratively by scientific teams from the University of Birmingham, Cambridge University, and FiberLean Technologies, this innovative coating presents a viable solution for effectively protecting high-traffic objects like door handles and handrails.

The coating comprises an invisible, abrasion-resistant cellulose fiber film, ideal for application on various surfaces such as glass, metal, or laminate. Unlike conventional disinfectants and antiviral designs that target specific viral components, the researchers, led by Professor Zhenyu Jason Zhang from Birmingham’s School of Chemical Engineering, focused on leveraging the porous structure of the film to desiccate respiratory droplets that harbor the viruses. This is achieved through the capillary force introduced by the film’s porous nature.

Previous studies have established that the COVID-19 virus can remain viable for days on plastic and stainless steel surfaces, while its infectivity diminishes within hours on newspaper. The interdisciplinary team, equipped with expertise in surface chemistry and formulation engineering, investigated the structure and efficacy of a coating composed of micro-fibrillated cellulose (MFC) supplied by FiberLean Technologies—a global leader in MFC production for the paper and packaging industry.

The researchers discovered that the porous structure of the film played a crucial role by accelerating the evaporation rate of liquid droplets and creating an imbalanced osmotic pressure across bacterial membranes. To evaluate the coating’s ability to prevent surface transmission of SARS-CoV-2, the team subjected droplets containing the virus to the film. They observed a three-fold reduction in infectivity after 5 minutes on the coating, with infectivity dropping to zero after 10 minutes. In contrast, infectivity was still present on a glass surface after the same duration. Similar reductions in infectivity were observed when droplets containing bacteria (E. coli and S. epidermidis) were tested at 1 hour and 24 hours.

The researchers extended their experiments to assess the film’s effectiveness in minimizing the transfer of respiratory aerosols by using aerosolized artificial saliva. The results indicated that the cellulose thin film successfully suppressed contact transfer.

Professor Zhang emphasized the significance of surface transmission risk compared to aerosol transmission. Larger droplets, which retain their infectivity on hard surfaces, pose a potential source of transmission through touch. The cellulose surface coating, developed using sustainable materials, has the potential to be combined with other antimicrobial agents, enabling long-lasting and slow-release antimicrobial effects.

Mechanical scraping tests confirmed the stability of the coating, as it exhibited no noticeable damage when dry but could be easily removed when wet, making it suitable for daily cleaning and disinfection practices.

The findings of this research have been published in the journal ACS Applied Materials & Interfaces.

Source: University of Birmingham

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