Is Nanotechnology the Answer?

The coronavirus pandemic generates interest in using nanotechnology as a potential antiviral treatment.

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Nanotechnology is the use of matter on a near-atomic scale, ranging between one to 100 nanometers. To a naked human eye, a nanoparticle is invisible, but this minuscule size makes nanotechnology particularly useful when manipulating atomic-sized particles such as viruses. In fact, nanoparticles have taken the world by storm as a prospective way to overcome the COVID-19 pandemic.

Nanomaterials have already been essential in the fight against SARS-CoV-2, as both the Pfizer–BioNTech and Moderna vaccines use lipid nanoparticles as a vehicle to deliver mRNA into cells. With the recent spikes in COVID-19 cases, many scientists are pushing for nanoparticles to play a more active role: halting the virus by binding and disrupting it.

What's more, the introduction of nanoparticles in antiviral therapeutics will be revolutionary. It is well known that viruses mutate as they are transmitted, which is responsible for the current variants of concern: the Delta and Omicron variants of SARS-CoV-2. Since traditional therapeutics normally target a specific virus strain, their effectiveness wanes as the virus mutates—this is why there is a new flu vaccine released every year. However, antiviral nanomaterials remove the need for a yearly vaccine by targeting common physical and chemical properties of viruses. They may contain additional advantages such as quick production time and high efficacy across different strains of viruses, which are urgently needed in this pandemic.

One nanomaterial-based antiviral technique plans to intercept viruses by using host cell decoys made from nanoparticles. Most viruses recognize and attach to receptors on host cell membranes using glycoproteins on its surface, however, researchers can create antiviral decoys by imitating these binding sites. Liangfang Zhang, a researcher at the University of California, San Diego, has employed this approach through nanosponges. The nanosponges are created through the process of emptying a human cell, leaving only the cellular membrane. Then the membrane is split into thousands of 100-nanometer wide vesicles, which will become the outer coat for the nanoparticles. The final product is a nanosponge that can envelop a virus and prevent it from infecting a host cell.

Zhang has achieved promising results with the nanosponges. Just recently, Zhang discovered that nanosponges with membranes from human lung epithelial type II cells, which are present on the surfaces of the body, or human macrophages can neutralize a SARS-CoV-2 infection in vitro, or outside of the organism. Moreover, an unpublished in vivo, or within the organism, study with mice produced results that confirmed the nanosponge’s efficacy against coronavirus and its negligible toxicity.

Another antiviral strategy traps viruses by using specially designed nanoparticles that maximize binding with viruses. The nanoparticle is shaped to match the virus’s morphology, allowing it to effectively halt infections. A team at the Free University of Berlin developed silica nanoparticles with tiny extruding spikes that lock onto the glycoprotein on a virus’s surface. The spikes can also be improved by mixing in sialic acid sugars to strengthen binding or adding antiviral compounds. In vitro experiments revealed that the nanoparticles were successful in treating cells infected with the influenza A virus. Now the team is pursuing a spiky nanoparticle to counter SARS-CoV-2.

Some antiviral nanomaterials directly disrupt the viral membrane instead of binding to viruses. The viral membrane is essential for initiating infections and keeping the virus’s structure intact; by compromising the viral membrane, the virus is unable to continue reproducing and maintaining its structure. A company named NanoViricide has implemented this strategy and uses nanoviricides as the disruptor. The nanoviricide structure contains 1,200 ligands that mimic viral targets like cellular receptors. Like nanosponges, nanoviricide attracts and binds to viral glycoproteins. When the binding occurs, the nanoviricide releases lipids into the viral envelope, destabilizing the viral structure and inactivating the virus. In vitro experiments demonstrated that mice with severe coronavirus survived substantially longer when treated with nanoviricide as opposed to traditional antiviral medications.

While nanotechnology is still a relatively novel field, it has been receiving overwhelming support and producing impressive results. Despite this, pharma and biotech companies are progressing cautiously with nanomaterial-based therapeutics until its safety and efficacy can be confirmed through adequate testing. It is uncertain whether there are permanent side effects, and many worry about the bioaccumulation of nanoparticles. However, the recent nanotechnology advancements in COVID-19 vaccines and antiviral therapeutics are the first steps in making it credible. As nanotechnology continues to storm ahead, it won’t be long before it becomes a trustworthy treatment against the coronavirus and other viruses.