As the current COVID-19 pandemic keeps evolving every day, researchers are focusing on ways to prevent, diagnose and treat the illness.
Coronaviruses, including SARS-CoV-2, MERS-CoV (Middle East Respiratory Syndrome) and SARS-CoV, cause a severe respiratory disease together with many complications.
People from all over the world already receive vaccine injections to prepare their immune system in case of an infection. But as time goes by, adaptive mutations in the SARS-CoV-2 genome can be observed (with the appearance and spread of variants), making it potentially more difficult to detect and treat.
Indeed, these mutations can lead to a certain questioning about the development of effective drugs and vaccines.
Analysis of the use of metallic nanoparticles
One of the solutions could be linked to nanotechnology, which carries a potential to participate in the fight against this viral disease.
Different strategies are being considered by the scientific community regarding the use of metal nanoparticles to fight SARS-CoV-2.
In a review published in November 2021, using metal nanoparticles in the treatment of coronaviruses is analyzed. Very few studies have been conducted for the moment. Therefore, scientists are very cautious, concerning the side effects that could emerge from this use.
This review (entitled “Metal Nanoparticles against Viruses: Possibilities to Fight SARS-CoV-2”) is available in the Journal “Nanomaterials” (https doi.org). It is also published on the National Library of Medicine’s.
Metal Nanoparticles as Antivirals
Antivirals are tools made to detect potential viral targets. They can also be used to develop our body’s immune response towards viral infections. Studies have revealed some promising strategies regarding nanoparticles antiviral approaches against SARS-CoV-2 virus.
Silver nanoparticles are particularly effective against bacteria and viruses. Indeed, scientists noticed that these particles could prevent viruses from attaching to host cells and therefore, avoid the replication of viral RNA and the spread of the infection.
Smaller Silver nanoparticles can even enter the cells to have a better interaction with the virus, but this process is quite hazardous: it can damage the host cells and cellular components, leading to a certain toxicity.
Copper nanoparticles also demonstrated some antiviral activity, but mainly concerning influenza A virus. The copper ions released on the surface of copper nanoparticles allow them to inactivate the virus in a concentrated way. According to a recent study, copper surfaces and materials have shown to be quite efficient regarding the inactivation of SARS-CoV-2.
Various oxide particles can also be used for their antiviral activity. If we take the example of zinc oxide nanoparticles and its effects on Influenza A virus, this type of metallic nanoparticles are real tools to inactivate the infected target cells.
Thanks to the Nanoparticles Delivery System, these particles can be used to transport specific drugs into infected cells, which are delivered and released when the targeted cells have been reached and infiltrated by the nanoparticle. However, studies revealed that using this method could cause damages to the host cell and could have a toxic effect.
Another metallic nanoparticle has been identified to detect and prevent Coronaviruses: Gold nanoparticle. It is used for diagnostic devices and vaccines, because they are chemically inert and nontoxic. Scientists have run some tests and set up a complex of gold nanoparticles. The test results showed they were extremely effective against virus infections.
Nanoparticle Delivery Systems against Viruses
The review also addresses the effectiveness of drugs. The main problems that have to be addressed are solubility, permeability and absorption.
These three factors determine whether the treatment is effective or not. To allow people to be better and longer protected, it is necessary to inject directly into the body some high doses of drugs. This may affect the patient with major negative side effects.
Metallic nanoparticles and their delivery systems could bring a solution and interfere directly with the replication of viruses. Indeed, nano-carriers would be able to improve the action of drugs since they are first injected with a particular drug. Then they are affected with a target ligand, specifically meant to bind with a receptive ligand, present on the surface of the infected cells.
Once the two are linked together, the nanoparticle or nano-carrier is absorbed in the infected cell and delivers the drug directly inside the cell that needs to receive the medicine. This delivery system makes sure that the drug is being carried correctly to the nanoparticle’s target.
To prevent severe virus infections, getting vaccinated is the most effective thing to do. Many vaccines have been developed to fight COVID-19 since the beginning of the pandemic, using various approaches (viral vector or DNA vaccines for instance).
Integrating metallic nanoparticles in vaccines could be very interesting. They have many advantages including boosting the immune system, thus strengthening the effects of vaccination.
Gold nanoparticles are already used within certain vaccines as adjuvants, which means that they are here to signal the infection and enhance the immune response. Due to their low toxicity and their stability, gold nanoparticles are harmless for the host cells. Gold nanoparticles are easy to synthesis and are usually used in Foot-to-mouth disease and Influenza A vaccines. Some studies are being conducted in order to know if it can be added to vaccines against Cancer, HIV, Hepatitis or Encephalitis.
Researchers have discovered that the use of these metal particles led to a better propagation of the T cells in the body when facing a virus. T cells are a key part of the immune system: these are a specific type of white blood cells meant to identify and attack infected cells to stop the spread of the infection. Apart from gold nanoparticles, few metal nanoparticles are used today in the vaccines due to their toxicity we have mentioned earlier and the danger they can represent to host cells.
But solutions might be developed in the future to face this issue. Gold nanoparticles could soon be integrated in the development of new vaccines to fight SARS-CoV-2, because of its low toxicity and chemical inertness.
Metallic nanoparticles in COVID-19 Diagnosis
Early detection of SARS-CoV-2 into someone’s system is extremely important. This diagnosis allows medical staff to contain both the spread in the patients’ body and the spread to other people.
The properties of metallic nanoparticles are responding to this need to detect the infection rapidly. Indeed, their electrochemical, fluorescence or magnetic resonance functions allow them to extract samples of SARS-CoV-2 from potentially infected cells, and to detect the infection quite quickly.
Magnetic nanoparticles coated with carboxyl polymer will allow them to extract nucleic acids and to separate SARS-CoV-2’s RNA, leading to the detection of the infection. Thanks to amplification methods, the sensitivity of the detection can be increased.
This review presents a broad spectrum of the various ways some metal nanoparticles could be used in the fight of SARS-CoV-2.