Jan 27, 2021 |
Ultra-absorptive nanofiber swabs could improve SARS-CoV-2 test sensitivity
(Nanowerk News) Rapid, sensitive diagnosis of COVID-19 is essential for early treatment, contact tracing and reducing viral spread. However, some people infected with SARS-CoV-2 receive false-negative test results, which might put their and others’ health at risk.
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Now, researchers reporting in ACS’ Nano Letters ("Ultra-absorptive Nanofiber Swabs for Improved Collection and Test Sensitivity of SARS-CoV-2 and other Biological Specimens") have developed ultra-absorptive nanofiber swabs that could reduce the number of false-negative tests by improving sample collection and test sensitivity.
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A new type of nanofiber swab could improve sample collection and test sensitivity for SARS-CoV-2 and other biological specimens; ruler at left shows centimeters. (© Nano Letters)
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Currently, the most sensitive test for COVID-19 involves using a long swab to collect a specimen from deep inside a patient’s nose, and then using a method called reverse transcriptase-polymerase chain reaction (RT-PCR) to detect SARS-CoV-2 RNA. But if the viral load is low, which can occur early in the course of infection, the swab might not pick up enough virus to be detectable.
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Jingwei Xie and colleagues wanted to develop a nanofiber swab that could absorb and then release more viruses and other biological specimens, improving the sensitivity of diagnostic tests.
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The researchers used an electrospinning technique to make 1-cm-long cylinders composed of aligned nanofiber layers, which they coated with a thin layer of gelatin and bonded to plastic swab sticks.
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In lab tests, the porous nanofiber cylinders absorbed and released more proteins, cells, bacteria, DNA and viruses from liquids and surfaces than the cotton or flocked swabs commonly used for COVID-19 testing.
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The team made dilutions of SARS-CoV-2 virus, swabbed the liquid samples and tested for viral RNA with RT-PCR. Compared with the two other types of swabs, the nanofiber ones reduced the false-negative rate and detected SARS-CoV-2 at a 10-times lower concentration.
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In addition to allowing more accurate and sensitive COVID-19 testing, the nanofiber swabs have far-reaching potential in diagnosing other diseases, testing for foodborne illnesses and helping forensic teams identify crime suspects from miniscule biological specimens, the researchers say.
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