Currently, the most sensitive test for COVID-19 involves using a long swab to collect a specimen from deep inside a patient’s nose or throat. A method called reverse transcriptase-polymerase chain reaction (RT-PCR) is then used to detect the RNA of the SARS-CoV-2 virus that causes COVID-19. However, 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.
Jingwei Xie, University of Nebraska Medical Center, Omaha, and University of Nebraska-Lincoln, USA, and colleagues have developed a nanofiber swab with significantly improved absorption of viruses and other biological specimens. This improves the sensitivity of diagnostic tests such as the COVID-19 test. The researchers used electrospinning and a gas-foaming technique to make cylinders with a length of 1 cm composed of polycaprolactone (PCL) nanofiber mats with aligned layers. The nanofiber mats were coated with gelatin and bonded to plastic swab sticks using an epoxy resin.
The resulting porous nanofiber cylinders absorb and release more proteins, cells, bacteria, DNA, and viruses from liquids and surfaces than the swabs commonly used for COVID-19 testing. The team prepared dilutions of the SARS-CoV-2 virus, swabbed the liquid samples, and tested for viral RNA with RT-PCR. They found that the nanofiber swabs reduced the false-negative rate and allowed the detection of SARS-CoV-2 at concentrations down to ten times lower compared with commercially available swabs.
According to the researchers, in addition to allowing more accurate and sensitive COVID-19 testing, the nanofiber swabs could have applications in diagnosing other diseases, testing for foodborne illnesses, or helping forensic teams identify suspects from very small biological specimens.
- Ultra-absorptive Nanofiber Swabs for Improved Collection and Test Sensitivity of SARS-CoV-2 and other Biological Specimens,
Alec McCarthy, Lorenzo Saldana, Daniel N. Ackerman, Yajuan Su, Johnson V. John, Shixuan Chen, Shelbie Weihs, St. Patrick Reid, Joshua L. Santarpia, Mark A. Carlson, Jingwei Xie,
Nano Lett. 2021.
Also of Interest
- Collection: SARS-CoV-2 Virus
What we know about the new coronavirus and COVID-19