You may have heard of nanoparticles. They have had negative news exposure as potentially dangerous pollutants when plastics break down, and for a time there were concerns about the possibility of nanoparticles in sunscreen also posing a danger.
But nanoparticles can be a force for good, say scientists, with new studies indicating vaccines constructed of nanoparticles may even offer strong protection against influenza.
What exactly are nanoparticles?
The use of the prefix ‘nano’ usually designates something extremely small. In fact, the word nano derives from the Greek νᾶνος (Latin nanus), meaning ‘dwarf’. In the metric system of measurement, nano has a more precise meaning – ‘one billionth’. A nanometre is one one-billionth of a metre. Even a micrometre, which is one one-thousandth of a millimetre, is almost too small to imagine. But a nanometre is one one-thousandth of a micrometre.
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Nanoparticles have a slightly less precise definition but are nevertheless unimaginably small. A nanoparticle – sometimes referred to as an ultrafine particle – is usually defined as a particle of matter that is between one and 100 nanometres (nm) in diameter.
Nanoparticles cannot be seen by the human eye. In fact, not even an optical microscope can distinguish one. Electron or laser microscopes must be used to study them.
How can nanoparticles make vaccines better?
The easiest way to answer this question is to picture the broccoli you buy at your local greengrocer. It consists of a floreat ‘head’ and a stalk. On a nanoscopic scale, the influenza virus looks very similar, consisting of a head and a stalk.
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Current vaccines attack the head of the influenza virus, but research has identified that the head of the virus evolves far more rapidly than the stalk. This means that the effectiveness of those vaccines is relatively short-lived.
However, the nanoparticle-based vaccines target the slower-evolving stalk, meaning they will potentially last longer and may take scientists one step closer to a universal influenza vaccine.
Where can I get my nanoparticle influenza vaccine shot?
It is not that simple just yet, although eventually it may be even simpler than getting a ‘jab’. The nanoparticle vaccines are not administered by a needle but, rather, intranasally – that is via a nasal spray not unlike those used to deliver a decongestant.
For humans, though, nanoparticle-based vaccines delivered via a nasal spray are still some way off. The latest research, published in January by the American Chemical Society, tested these vaccines on mice, and human trials remain a way off too.
Potential side-effects will also need to be considered. Corresponding author of the study Dr Baozhong Wang, a professor at the Institute for Biomedical Sciences at Georgia State University, explained that “challenges exist to the successful research and development of nanoparticle vaccines. Though no apparent adverse effects were observed in the study, a more comprehensive safety evaluation of the nanoparticle adjuvant system is needed before clinical trials.”
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Nevertheless, the early indications are promising. The new vaccine, which consists of nanoparticles known as PEI-HA/CpG and delivered by a robust and versatile delivery system called PEI (polyethyleneimine), can simultaneously carry antigens, which induce an immune response in the body, and adjuvants, which enhance the body’s immune response to an antigen. This helps to provide what the study describes as “optimal immunoenhancement”.
That extremely technical-sounding term means better protection against the flu is heading our way – hopefully sooner rather than later.
Does the idea of a nanoparticle-based vaccine excite you? Do you think it would provide better protection against the flu? Why not share your thoughts in the comments section below?
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