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As the quest for a COVID-19 vaccine continues, researchers working in other areas of science such as nanotechnology have joined the battle against the virus.
In addition to being responsible for hundreds of thousands of deaths, the COVID-19 crisis has mobilized the scientific community in a way that no other situation has before. Multiple disciplines are currently researching the virus, whether this be developing diagnosis and treatment methods, or a modality to slow its spread.
Nanotechnology is being prepared for deployment in the fight against COVID-19 in a wide range of areas. A new paper published in the journal ACS Nano looks at the different ways in which nanotechnology will be used, with the authors describing the use of nanotech in fields as diverse as virology, biology, medicine, engineering, chemistry, materials science, and computational science.
The nanotechnology breakthroughs made in the coming months and years should not just bolster the resistance against COVID-19, but also help in the fight against other viruses, bacteria, and pathogens.
The authors of the study identified four key stages at which nanotechnology could be introduced to help the battle against COVID-19:
- As an alternative to disinfectants preventing the virus spread
- In diagnostic procedures
- Delivering drugs to those already infected
- Suppressing the immune response of COVID-19 patients
What follows is a rundown of the methods being developed that could be employed in future pandemics and epidemics, possibly preventing them from reaching global crisis status.
Slowing the Spread
The ongoing COVID-19 crisis does not mark the first time that nanomaterials have been highlighted for their ability to limit the spread of viruses. Surfaces coated with polymers containing nanoparticles of metals such as copper can release metal ions, which are known for their antiviral activity and have already been suggested for use in certain areas. The widespread nature of the COVID-19 crisis calls for a corresponding widespread application of such measures.
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Nanotechnology offers a safer alternative to the use of toxic chemicals such as disinfectants in medical settings. Such coatings are far more convenient than other non-toxic disinfectant measures such as irradiation with ultraviolet (UV) light. These nanomaterial coatings and alloys confer antiviral and antibacterial properties through the release of ions, which disrupt the operation of living cells.
One of the key difficulties in tackling COVID-19 is its hardiness and ability to survive on a variety of surfaces for prolonged periods — often days on end. The beauty of a nanomaterial coating is that it could provide protection continuously after just one treatment. This is especially true if the material can be structured in such a way that the release of ions is gradual. ‘Self-disinfecting’ surfaces would be of great use even after the COVID-19 crisis is over.
Silver, copper and zinc all show intrinsic antimicrobial properties and are already used in medical equipment and healthcare settings.
In unison with our growing understanding of bacteria and viruses, silver nanoparticles have found their way into commercial products such as silver zeolites in paints, and in food trays as a biocide, with the antiviral efficiency of silver nanoparticles demonstrated against a variety of viruses, including HIV-1.
Copper was shown to be effective against polio in the late 1970s and, more recently, was of great use in combating another coronavirus, HuCoV-229E. The virus, which typically lives for around six days on a surface, became inactive in approximately 60 minutes on surfaces coated with copper alloys. The similarity between HuCoV-229E and SARS-CoV-2 points to copper nanoparticles and alloy coatings being a key-player in slowing, if not stopping, the spread.
The authors suggest that copper alloys could also find themselves replacing more traditional stainless steel surfaces and appliances in medical settings as a result of this non-toxic antibacterial agency.
Nanomaterials are also employed in the production of vitally import personal protective equipment (PPE) to help reduce the spread of COVID-19 to frontline medical workers. In particular, nanomaterials could be used in facemasks and other PPE to capture and immobilize viral cells. This task would likely fall upon silver nanoparticles, which have been shown effective in this respect, severely limiting viral activity when loaded into filters.
Find out more about nanomaterials in several industries
However, even if the spread of COVID-19 can be slowed by such coatings and a switch to copper alloys, another vital step in combating COVID-19 is efficient testing and diagnosis. Fortunately, nanomaterials are on hand to aid in this regard too.
Using Nanoparticles in COVID-19 Testing
The SARS-CoV-2 virus cannot be eliminated from all surfaces, and not all surfaces can be coated with a nanomaterial layer. This means that even with such measures, the transmission is very likely to continue. Therefore, the next step in slowing the spread is the quick and effective diagnosis of those already infected.
The current testing methodology for COVID-19 involves the use of a swab applied to the throat and nasal passage of a potential patient. This swab is then analyzed using a reverse transcription-polymerase chain reaction (RT-PCR) test — a procedure used in virology to test for the presence of specific RNA. The use of nanoparticles, however, could provide a more immediate ‘on-site’ test result without the need to send samples away for lab analysis or the need for expensive equipment.
The principle behind the application is the binding of gold nanoparticles with antibodies and is in its very early planning stages. In the presence of further antibodies collected from the patient, the nanoparticles cluster, shifting the color of the test swab from blue to red. This provides an immediate indication of infection. A test of this nature could be of particular use in developing countries and regions of the world with little to no medical infrastructure.
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Another alternative to the currently favored RT-PCR test is graphene-based field-effect transistors (FET), which are biosensing devices coupled to a specific antibody against SARS-CoV-2 spike protein. Again, this would be another method of on-site detection of COVID-19 that is cost-effective and delivers a rapid result.
Gold nanoparticles can also be used in nano biosensors, which combine the excellent electrical and optical properties of nanomaterials with biological or synthetic molecules used as receptors to detect specific whole viral cells selectively. This cell-sensing device is based on the reaction of cell surface proteins with specific antibodies conjugated to gold nanoparticles taking advantage of the known antigens and available antibodies.
It should be noted that this is a field in its relative infancy, but any developments spearheaded in response to the COVID-19 crisis could be carried forward to future epidemics and pandemics.
Deactivating SARS-CoV-2 in Patients
The rapid spread of COVID-19 and the relative failure to tackle it has exposed a weakness in medicine: the lack of a broad-spectrum antiviral drug. That means that when a new virus emerges, there is little in the way of medical intervention that can be done to mitigate the spread. Therefore, drugs that could tackle both COVID-19 and future viruses are of the utmost importance.
Though other organs can be affected, the main target of COVID-19 once inside the body of a sufferer is the respiratory system. In particular, the virus targets the upper respiratory tract and the lungs, with the latter being the most critically affected area. Therefore, the review paper focuses on methods that seek to inactivate the virus in the deep-lung.
Airborne nanomaterials can penetrate the deep-lung, delivering medicine directly to the cells that SARS-CoV-2 uses to spread further into a patient’s system. Nanomedicine is currently being heavily researched in terms of providing drugs and using beneficial proteins via aerosol nano-devices.
A general antiviral nanomaterial intervention could work by preventing viruses from interacting with and binding to cell membranes. Previous work has shown that this could possibly be achieved by a wealth of nanomaterials such as polymers, liposomes, and small molecules.
However, the implementation of these methods via aerosol has been hampered by the necessary dilution of these nanomaterials, which negatively impacts their effectiveness. This loss of efficiency allows virus cells to begin replication again.
This setback can be combated by nanoparticles that, after introduction to a patient’s lungs or other organs, attack the virion —the infective form of a virus outside a host cell — permanently damaging it and stopping replication.
A specific COVID-19 drug administered in a similar way to the general antiviral treatment discussed above could be created by engineering it to block the S spike protein from interacting with the ACE2 receptor.
Part of the key to saving the lives of COVID-19 patients may not just hinge on attacking the virus, but limiting the body’s response to it.
Your Own Worst Enemy: Suppressing the Immune Response with Nanotools
As a result of the COVID-19 crisis, many more people are familiar with the phrase ‘Cytokine Storm’. Cytokine storms are associated with a wide variety of infectious and noninfectious diseases, in particular the H1N1 influenza strain. The term itself summons images of a terrible and violent reaction within the patient’s body, arising from their excessive immune response.
Although a well-regulated cytokine response that is rapidly triggered by the host’s innate immunity can serve to prevent and counteract infection, an excessive, unbalanced and prolonged immune response can seriously harm the body.
In many COVID-19 cases, this inflammatory storm is responsible for acute respiratory distress syndrome (ARDS), which is often associated with multiple organ failure and a leading cause of death in critical patients.
Nanomaterials have been used to adjust the immune response, bringing it to an optimal level, and could be used to limit the cytokine storm. This can be done in a number of ways.
Firstly, nanotechnology can deliver immunosuppressants to target immune cells and organs, leading to reductions in drug dose, drug distribution to non-target tissues and organs, and, in-turn, unwanted side effects.
Secondly, nanotools can be explicitly designed to evade the immune system and finely tune the patient’s system to receive a high drug load that could otherwise trigger a harmful immune response.
With regards to COVID-19 specifically, the authors of the review point to the use of nanodiamonds to reduce macrophage infiltration — a process linked to inflammation.
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COVID-19 and Beyond
COVID-19 has presented the scientific community with the kind of challenge it has perhaps never had to face before, but it has also created the awareness that this situation could arise again.
The nanotech advancements described, while being engineered in response to this current crisis, are designed by scientists with an eye to the future and the next potential pandemic.
The authors of the review paper have a message to the general public, policy-makers, politicians, and the scientific community: we must stop thinking of human health as an isolated phenomenon. Instead, we have to embrace the concept of ‘one health’ with understanding that our well-being is intrinsically and irreversibly linked with the ecosystems we inhabit.
The field of nanotechnology points towards the benefits of adopting a holistic and inclusive attitude, spreading across so many aspects of science and bringing together scientists from diverse backgrounds, all converging on a multifaceted solution to a crisis that threatens our very way of life.
The study of nanotechnology could emerge such big ideas with the capability of changing the world.
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References and Further Reading
Weiss, C., Carriere, M., Fusco, L., et al. (2020) Toward Nanotechnology-Enabled Approaches against the COVID-19 Pandemic. ACS Nano. https://doi.org/10.1021/acsnano.0c03697.
Lea, R. (2020) The Development of a New Anti-COVID-19 Nanocoating. [Online] AZO Nano. Available at: https://www.azonano.com/news.aspx?newsID=37294.
Lea. R. (2020) Graphene-Based Masks Launched to Combat COVID-19. [Online] AZO Nano. Available at: https://www.azonano.com/news.aspx?newsID=37431.