Control of viruses may be one of the most important, as well as difficult, challenges facing the world of healthcare. Not only does this cause a work burden for those in the healthcare industry, but it also poses an economic burden to those who are infected. When considered across the entire population, non-influenza-related infections, such as rhinovirus and coronavirus, account for an estimated $40 billion annually in direct and indirect costs in the United States.[1] Whether ubiquitous in nature, such as norovirus, seasonal like rhinovirus, or pandemic like the all too familiar SARS-CoV-2, viruses can be difficult to inactivate due to a variety of reasons, but mostly attributed to their stable nature, high infectivity per particle, and general resistance to disinfectants.[2] [3] An unfortunate consequence of being difficult to inactivate, viruses can last on surfaces for an extended period of time. Self-inoculation then becomes a concern when people touch these contaminated objects and then proceed to touch their face, thus transmitting the virus into their nose, eyes, and mouth. Inactivating these viruses as they lie on surfaces waiting for someone to pick them up could be a health and cost-saving measure taken to keep the threat of infection at bay. Today we will look at a study done on the technology that powers NanoRAD, and how its residual disinfecting qualities are used to keep these viruses at bay.
Importance of Residual Disinfectants
Residual disinfectants refer to chemical agents that remain active even after the initial application, providing ongoing protection against microorganisms. This ensures that surfaces and areas remain disinfected even after the initial application, reducing the risk of recontamination, especially in settings where frequent cleaning and disinfection may not be feasible, such as hospitals, public transportation, or high-traffic areas. Residual disinfectants also create a consistent layer of protection, which can help maintain a safer environment for a longer duration between cleaning cycles. They also help mitigate the risk of human error in cleaning protocols. Even if an application on a surface is missed during cleaning, a residual disinfectant can still provide protection from the previous application, depending on its efficacy over time. When looking at the spread of viruses, residual disinfectants play a crucial role in reducing the spread of infections, especially in environments with a high potential for disease transmission, such as healthcare facilities where transmission could be heightened among patients, healthcare workers, and visitors. NanoRAD is an on-demand residual disinfectant that produces targeted hydrogen peroxide when in the presence of bacteria and viruses. As long as the treated surface has access to the water in the air, it stays effective against these pathogens.
Journal Publication
A follow-up to the previous journal (which has its own blog post linked here), this one investigates the efficacy of the nanoparticles against non-enveloped viruses, such as mutant Rhinovirus 14, selected to be resistant to oxidation. Testing again occurred at the University of Central Florida on the technology that powers NanoRAD.
- Broad-Spectrum, Potent, and Durable Ceria Nanoparticles Inactivate RNA Virus Infectivity by Targeting Virion Surfaces and Disrupting Virus–Receptor Interactions [4]
Review of Problem and Solution
As a quick refresher before going over the results of the journal publication, let’s go over again the different classifications of viruses, the issues that they each pose, as well as why the nanoparticles in NanoRAD can provide a solution to this problem.
There are two main classes of viruses, those that are “enveloped” whereas others are considered “non-enveloped”, and their kill mechanisms can be different. In an enveloped virus, where a glycoprotein or other surface structure exists, the easiest way to render them non-infective is to break down this outer structure. A non-enveloped virus, however, lacks a lipid membrane and instead has an outer protein coating that protects the virus. To render this non-infective, damage to the protective protein coating on the virus must occur, causing it to be incapable of infecting cells. The basic antimicrobial mechanism needed to prevent infection by a virus is the disruption of the surface proteins that allow the virus to enter and infect a cell. Surface oxidation, which can be achieved with the use of a disinfectant like hydrogen peroxide, achieves the breakdown of these surface proteins on viruses. In this study, a mutant Rhinovirus-14 was selected to test against as a non-enveloped virus, which is resistant to oxidation.
Because of the persistence of infective viruses on surfaces, solutions other than single-use disinfectants have been presented to combat these viruses, including the use of metal and metal oxide nanomaterials. These nanoparticles, like the ones that power NanoRAD, are comparable to native enzyme behavior and are considered enzyme-mimetic. NanoRAD’s artificial enzyme behavior allows the redox-reactive nanomaterials to create oxygen vacancies which allow them to produce oxidizing species, such as hydrogen peroxide.
When it comes to deactivating viruses, enzyme-mimetic nanomaterials can be engineered to target specific components or processes essential for the virus’s survival and replication. The oxidation properties of these nanoparticles allow them to attack both kinds of viruses, attacking the lipid membrane in the enveloped as well as degrading the structures of the non-enveloped kinds.
Results
Against the enveloped coronavirus OC43, one formulation of the nanoparticles was able to reduce the treated sample to below the detectible limits of infectivity after 4 hours. The untreated sample stayed above 104 TCID50/ml after starting near 105, over a 4-log reduction! Another formulation of the nanoparticles showed even better efficacy against the non-enveloped RNA virus Rhinovirus-14. Untreated samples stayed close to 106 TCID50/ml throughout the duration of the test, whereas the treated sample was reduced to a bit above 101 after 5 minutes, and after 2 hours, inactivated RV14 to undetectable limits of infectivity.
Conclusion
From this study, the technology that powers NanoRAD has shown great efficacy against both enveloped and nonenveloped viruses. Pair this with its residual qualities which result in fewer applications over a given time, requiring less manpower, and thus decrease the risk of human error in your facility’s disinfection protocol, and NanoRAD seems like the smart choice for decreasing the likelihood of surface-level infections in your facility.
[1] Fendrick AM, Monto AS, Nightengale B, Sarnes M. The Economic Burden of Non–Influenza-Related Viral Respiratory Tract Infection in the United States. Arch Intern Med. 2003;163(4):487–494. doi:10.1001/archinte.163.4.487
[2] Knipe, D.M.; Howley, P. Fields Virology; LWW: Philadelphia, PA, USA, 2013; Volumes 1 and 2.
[3] Lin, Q.; Lim, J.Y.C.; Xue, K.; Yew, P.Y.M.; Owh, C.; Chee, P.L.; Loh, X.J. Sanitizing agents for virus inactivation and disinfection. View (Beijing) 2020, 1, e16.
[4] Molecules | Free Full-Text | Broad-Spectrum, Potent, and Durable Ceria Nanoparticles Inactivate RNA Virus Infectivity by Targeting Virion Surfaces and Disrupting Virus–Receptor Interactions (mdpi.com)
