anti viral coating
Figure 1: Anatomy of COVID-19 Virus (Figure from New Scientist Journal)

As declared by World Health Organization (WHO), presently the whole world is facing a pandemic and a global crisis caused by a novel virus that was discovered to be the cause of a large and rapidly spreading outbreak of respiratory disease, including potentially fatal pneumonia, in Wuhan, China (starting January 9, 2020). The virus was provisionally designated 2019-nCoV and later given the official name SARS-CoV-2, the disease caused by the virus was officially named Coronavirus Disease 2019 (Covid-19) by WHO.

The SARS-CoV-2 is an enveloped, positive sense, single-stranded RNA virus. Coronaviruses are so named because of their characteristic solar Corona (crown-like) appearance when observed under an electron microscope. This appearance is produced by the peplomers of the surface (or spike; designated S) glycoprotein radiating from the virus lipidenvelope1.The SARS-CoV virion is spherical with an average diameter of 78 nm. 

anti viral coating

Figure 1: Anatomy of COVID-19 Virus (Figure from New Scientist Journal)

SARS-CoV-2 is delicate but highly contagious virus capable of spreading primarily from person to person around the world. It also spreads when an infected person cough or sneezed and a droplet landed on a surface or object, a person when touches that surface has the virus on it, then touches nose, mouth or eyes, could pick it up. On the personal level hygiene measures are recommended to prevent the spread of disease, especially in the institutions where individuals are in contact with patients or contaminated fomites. Washing hands with soap and water or with alcohol-based hand rubs is effective for interrupting virus transmission. Although viruses don’t grow on any nonliving surfaces but recent studies show Corona viruses can  remain viable or infectious on metal, glass, wood, fabrics and plastic surfaces for several hours to days, irrespective of the surface looking dirty or clean. Though, the Coronaviruses are relatively easy to destroy, using simple disinfectants like ethanol (62-71%), hydrogen peroxide (0.5%) or sodium hypochlorite (0.1%)2by breaking the delicate envelope that surrounds the tiny microbe. However, it’s practically impossible to sanitize the surfaces all the time and it doesn’t guarantee that the surface won’t get contaminated again. It’s a much wiser solution in such a scenario if the surface can repel the pathogens, making it nonstick and/or ‘sanitize by itself’ by neutralizing the contaminated pathogens quickly, thus eliminating the possibilities of transfer of microorganism to human body and its subsequent spreads. Study shows that the spike glycoprotein of COVID-19 allows the virus to dock and bind to the ACE2 surface proteins of human epithelial cells in the respiratory track, thereby infecting these cells. Association of the COVID-19 spike glycoprotein with host ACE2 surface protein is a crucial step for infection.  

Our research aim is to create surface coating with relatively low surface energy value which may repel the spike glycoprotein to anchor the surfaces of landing, also use of active chemicals those could inactivates the spike glycoprotein as well as viral nucleotides. As we already have developed an anti-microbial coating solution virtually for all surfaces with effective combination of nano-actives, having proven literature support as anti-virus too, we are pretty convinced about its performance as an antiviral too and this should resist the transmission of virus from nonliving articles to living body cells by touch. 

Literature survey shows that the nano-particles (NPs) of various metals and metal oxides like Zinc Oxide nanoparticles (ZnONPs)3, Cuprous Oxide nanoparticles (CuONPs)4, Silver nanoparticles (AgNPs)5,6, Nano sized Copper (I) Iodide particles (CuINPs)7,Gold nanoparticles on Silica nanoparticles (Au-SiO2NPs)8 and also some Quaternary ammonium cations commonly called QUATs9 are very promising to inactivate virus and are well proven

The product we have developed, NANOVA® HYGIENE+TM as an antimicrobial coating for the surfaces like fabrics, plastics, metals and concretes contains the cocktails of non-migratory QUATs and positively charged AgNPs as bioactive nanoparticles and dispersing this into binder polymers. This anti-microbial coating also shows extremely low surface energy value (>20 mN/m)10 and behaves as an omniphobic surface by repelling water and oil together. Contact angels were>130o and >50o when measured against water and hexadecane as probes10, respectively. This coating has proven test reports11 on protection against bacteria pathogens up to 99.9% as per the global standard JIS Z2801. The coated surfaces also have evidence to work effectively against fungi12and algae pathogens.

From available published data in literatures, we can safely opine that NANOVA® HYGIENE+TM would be a potential coating candidate to repel and inactivate Virus on the surface, hence could be a potential material to address the present problem of COVID-19 spread through surface touch.

The plausible ways of functioning of the doped nano actives materials against COVID-19 viruses would be as follows:

  1. As AgNPs has been reported to inhibit the replication of virus nucleotides, main mechanism of its being virulent. It binds to electron donor groups such as Sulfur, Oxygen, and Nitrogen commonly found in enzymes within the microbe. This causes the enzymes to be denatured thus effectively incapacitating the energy source of the cell and the microbe will quickly die
  2. The cationic silver (Ag+)or QUATs might work to inactivate the SARS-CoV-2 by interacting with its surface (spike) protein S based on its charge like it works in HIV, Hepatitis viruses, etc.5,6.
anti viral coating 2

Figure 2 : Schematic repetition of anti-viral coating with our nano-actives for inactivation of any adhered virus on the surfaces

As NANOVA® HYGIENE+TM omniphobic antimicrobial coating shows complete disablement of various pathogenic bacteria already and further on the basis of available scientific supports, we are in opinion that the present formula should work against a broad spectrum of viruses as well. However, test and validation are being conducted in war footing at South India Textile Research Association (SITRA), Coimbatore to establish its efficacy on inactivation of COVID-19 on different surfaces to stop the secondary spread from various surfaces to living cells through touch. Once find active, it has numerous applications virtually for all surfaces like fabric (mask, gloves, doctor coats, curtains, bed sheet), Metal (lifts, doors handle, nobs, railings, public transport), wood (furniture, floors and partition panels), concrete (hospitals, clinics and isolation wards), plastics (switches, kitchen and home appliances) and potentially could save many lives.

ACKNOWLEDGMENTS

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I would like to thank Dr Santanu Dasgupta, Dr Chitranshu Kumar and Dr Manish R. Shukla of Reliance Industries Limited for their help in facilitating validation studies to test efficacy against different viruses and for their technical inputs in preparing this document.

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