17-Apr-2020 - American Chemical Society (ACS)

New COVID-19 test quickly and accurately detects viral RNA

Millions of people have been tested for the novel coronavirus, most using a kit that relies on the polymerase chain reaction (PCR). This sensitive method amplifies SARS-CoV-2 RNA from patient swabs so that tiny amounts of the virus can be detected. However, as the pandemic surges, this laboratory workhorse is showing signs of strain. Now, researchers reporting a proof-of-concept study in ACS Nano have developed a potentially more accurate diagnostic based on plasmonic photothermal sensing.

Health experts agree that expanded testing is crucial for controlling the spread of COVID-19. However, testing in many countries, including the U.S., has lagged behind because of limited supplies of some reagents and a backlog of samples awaiting available PCR machines and laboratory personnel. In addition, a number of false-negative and -positive test results have been reported. Other methods, such as computed tomography (known as "CT") scanning and culturing, do not provide quick or real time results. Jing Wang and colleagues wanted to develop a faster, potentially more accurate COVID-19 test for detecting the SARS-CoV-2 virus that could be a practical alternative to PCR.

The researchers based their test on a technique called localized surface plasmon resonance, which can detect interactions between molecules on the surface of a constructed metallic nanostructure as a local change in refractive index. The team made DNA probes that recognized specific SARS-CoV-2 RNA sequences and attached them to gold nanoparticles. When they added pieces of the virus's genome, the RNA attached to the complementary probes like a zipper being closed. The team used a laser to heat up the nanoparticles, making it more difficult for imperfectly matched sequences to remain attached, reducing false-positives. For example, a nucleic acid "zipper" missing a couple of teeth -- indicating a partial mismatch -- would unzip under these conditions. In this way, the researchers could discriminate between SARS-CoV-2 and its close relative, SARS-CoV-1. The assay detected amounts of viral RNA below those present in respiratory swabs in a matter of minutes. Although the test still needs to be tested on intact viral RNA from patient samples, it could help relieve the current pressure on PCR-based tests, the researchers say.

American Chemical Society (ACS)

Recommend news PDF version / Print

Share on

Facts, background information, dossiers
  • coronaviruses
  • SARS-CoV-2
  • diagnostics
  • Covid-19
  • surface plasmon resonance
More about American Chemical Society
More about ETH Zürich
  • News

    Mechanism discovered how the coronavirus hijacks the cell

    Researchers at ETH Zurich and the University of Bern have discovered a mechanism by which the corona virus manipulates human cells to ensure its own replication. This knowledge will help to develop drugs and vaccines against the corona virus. Like a pirate hijacking a ship, a virus takes co ... more

    Electron movements in liquid measured in super-slow motion

    Electrons are able to move within molecules, for example when they are excited from outside or in the course of a chemical reaction. For the first time, scientists have now succeeded in studying the first few dozen attoseconds of this electron movement in a liquid. To understand how chemica ... more

    A new biosensor for the COVID-19 virus

    A team of researchers from Empa, ETH Zurich and Zurich University Hospital has succeeded in developing a novel sensor for detecting the new coronavirus. In future it could be used to measure the concentration of the virus in the environment - for example in places where there are many peopl ... more