New test for COVID-19 could be more effective, says studyLast updated on Apr 16, 2020, 03:49 pm
Around the world, millions have been tested for the coronavirus disease (COVID-19) using RT-PCR technology.
RT-PCR, or reverse transcription polymerase chain reaction, works by amplifying the viral RNA obtained from infected persons. However, the technique has its own flaws.
Researchers in Switzerland have now come up with a new technique that could possibly be more effective and deliver results in minutes.
New technique presented by ETH Zurich researchers
Researchers at the ETH Zurich in Switzerland have presented a proof-of-concept study, published in the ACS Nano journal on Monday.
The study is titled 'Dual-Functional Plasmonic Photothermal Biosensors for Highly Accurate Severe Acute Respiratory Syndrome Coronavirus 2 Detection'.
It details the use of localized surface plasmon resonance (LSPR) sensing using dual-functional plasmonic photothermal (PPT) for detecting the novel coronavirus SARS-CoV-2.
How does the technique work?
Localized surface plasmon resonance is a phenomenon that refers to the collective oscillation of electrons on metallic nanoparticles when excited by incident photons at a resonant frequency.
The ETH researchers' LSPR system incorporates DNA probes that recognize RNA sequences specific to SARS-CoV-2. These probes are attached to two-dimensional gold nanoislands, or AuNIs.
These AuNIs are then illuminated at their plasmonic resonance frequency.
Technique promises reduced false-positive test results
The DNA probes are only sensitive to SARS-CoV-2 RNA sequences, i.e., any similar genetic sequences will only be imperfectly attached to the probes.
With the use of localized PPT heat, it becomes harder for imperfectly matched sequences to remain attached. This helps reduce the chances of false-positives.
This system can help detect SARS-CoV-2 of concentrations as low as 0.22 pM in a multigene mixture.
'Imperfect match like a zipper missing a few teeth'
A GEN report described this as, "Essentially, the DNA probes attach to complementary viral RNA like a zipper being closed." The report compared an imperfectly matched sequence to "a nucleic acid 'zipper' missing a couple of teeth" that would "unzip under these conditions."
Pros and cons
New technique could be more accurate, faster
GEN reported that the equipment used for SPR would be more expensive and is only made by a handful of companies.
However, SPR systems also require lesser biological reagents and can generate results in a few minutes.
The pros could prove to be an advantage against RT-PCR, where limited supplies of some reagents has hampered testing. It's also known to produce false-negatives and -positives.