COVID-19 Diagnostics: New COVID-19 Diagnostic Accurately Detects SARS-CoV-2 Coronavirus RNA in Minutes
: To date, millions of individuals have been tested for the SARS-CoV-2 coronavirus, most using a kit that relies on the polymerase chain reaction (PCR). This sensitive method amplifies SARS-CoV-2 RNA from patient swabs using a thermocycler machine so that tiny amounts of the virus can be detected. But as the crisis surges, this laboratory technique that is time consuming and taxing, is showing signs of strain.
Biotech researchers reporting a proof-of-concept study published in the journal ACS Nano
have developed a potentially more accurate diagnostic based on plasmonic photothermal sensing. https://pubs.acs.org/doi/10.1021/acsnano.0c02439
Medical professionals agree that expanded testing is crucial for controlling the spread of COVID-19. However, testing in many countries, including in America and Europe 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 or CT scanning and culturing, do not provide quick or real time results.
Dr 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 biotech 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 RNA 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 instance, 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.
The team is already working with a few commercial entities to start initial prototypes for regulatory approvals before going into mass production.
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