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Uploaded:2020-12-18
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Traditional COVID tests take time and specialized personnel, but a new kind of test that uses nanotechnology could expedite the process.

Hosted by: Hank Green

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Sources:
https://doi.org/10.1021/acsnano.0c02624
https://doi.org/10.1016/j.talanta.2020.121704
https://doi.org/10.1007/978-981-15-4280-0_4
https://doi.org/10.1016/j.jiec.2019.04.037
https://doi.org/10.1007/s00604-020-04615-x

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[♪ INTRO].

Though they’re perhaps not as  glamorous as medicines or vaccines,   diagnostic tests play a central  role in pandemic management. It’s just really hard to do much  of anything if you don’t know who   actually has the germ in question.

And for COVID-19 specifically, researchers pulled  out all the stops to design accurate tests. These tests have some drawbacks, though. Like,   they require experienced personnel, and  the results aren’t exactly instant.  So what if I told you that in the future, we  could be diagnosing infections like COVID-19   in five minutes or less with a  test people could give themselves?

That’s the hope of new research recently  published in the journal ACS Nano.  In a proof-of-concept paper, researchers  detailed a different kind of test   that can produce reliable COVID  results in under five minutes!  Step one of any COVID test is to  get a sample from the patient.  This often involves one of those long nasal  swabs to grab some fluids or a vial of blood. After that, there are a couple main  options — each with downsides.  One approach is to test for antibodies.  These are Y-shaped immune proteins that   are specific to a particular germ, so they  can help stop infections in a targeted way. And since they’re specific, they can also tell  doctors what germs have recently attacked.

The major downside here is  that it can take days or even   weeks for the body to start producing  enough antibodies to be detected,   so if the infection is still in the early  stages, this kind of test is unreliable. Also, antibody testing requires blood samples,  which must be collected by trained personnel.  That’s why many of the most commonly used tests  screen samples for the genetic code of the virus   lurking in bodily fluids.  Like all coronaviruses, SARS-CoV-2 is an RNA  virus, so these tests look for viral RNA. But RNA molecules are too small to just   see, and it’s not like a person’s  bodily fluids are packed with them.  So generally, to accurately detect an infection,   you first have to make lots  of copies of the viral RNA.  And that process can take a while.

Plus,  it tends to require specialized equipment,   chemicals, and personnel.  To solve these limitations, the research team  behind the new paper turned to nanotechnology.  Rather than relying on  amplifying what’s in the sample,   they designed a small biosensor chip that  can detect tiny amounts of SARS-CoV-2 RNA. The sensor consists of filter  paper coated with graphene:   a honeycomb-like lattice of carbon atoms  that is super-thin and very conductive. On top of this graphene layer are gold  nanoparticles, which are also very conductive.

And attached to these gold nanoparticles  are specially-designed strands of DNA.  These snippets of DNA act as probes  by specifically binding to parts of   the virus’s RNA genome — specifically,  chunks of a piece called the N-gene,   which codes for one of the virus’s  important structural proteins. In fact, the chip actually uses   multiple DNA detector strands to target  two different sections of this gene.  This means that even if the virus in  the sample has a mutation on one part,   it can still be detected. Anyhow, the binding of the  viral RNA to these DNA probes   creates a change in the electrical  charge of the molecules.

And since gold and graphene  are both highly conductive,   the electrical signal travels  across the paper to a circuit   to deliver it to a computer, which  then spits out the positive result. The team tested these sensor  chips on 48 clinical samples,   about half of which were known to  be infected based on standard tests. Not only did the chip correctly distinguish  between the infected and non-infected samples,   on average, the results were  delivered in under five minutes.

That kind of fast turnaround is  awesome for so many reasons! Like,   infected patients can start treatment sooner, and  negative patients aren’t waiting and worrying. And the researchers claim the test is just as,   if not more sensitive than the  ones currently being used.  Plus, it could spot different amounts  of the virus—what experts call the   viral load—which is super useful for  understanding infection dynamics.   But what’s really exciting  here is that this kind of test   could change how we spot infections in general.  For one thing, the materials  needed are relatively inexpensive.   The researchers suggest chips like  this could be sold for about $10 each.  They’re also super portable and can be  integrated with all kinds of computers,   including smartphones, so they could be  used in a doctor’s office or at home.

And in theory, scientists could design similar  rapid-testing chips for any virus — new or old!  So not only could this be a  new way of detecting COVID-19,   it could lead to more rapid and accessible  tests for all sorts of diseases,   which would be a boon for patients,  doctors, and researchers alike.  Though, first, these sensors are going to have to  prove themselves to oversight agencies like the  . US FDA, which probably means in-depth testing  and comparison to other tests on the market.  And someone will have to figure  out how to mass produce the chips,   as well as the hardware and software  needed to actually run the test.  So I wouldn’t expect these tests  to be everywhere, like, tomorrow.  Still, it’s pretty cool to see technologies  like this coming into their own — and I   wouldn’t be surprised if nanobiosensors  soon become all the rage in medicine.  Thanks for watching this episode of  SciShow News! And a special thank   you to Matthew Brant, our President of Space!

We here at SciShow salute you Matthew! And   we’re truly grateful to have you as a  part of our awesome patron community. If you want to learn more about joining  that community — including how you, too,   could be President of Space — you can  head on over to Patreon.com/SciShow. [♪ OUTRO].