New Ultra-Absorptive Nanofiber Swabs Could Improve COVID-19 Test Sensitivity

A team of researchers has developed an ultra-absorptive nanofiber swab that could reduce the number of false-negative COVID-19 tests by improving sample collection and test sensitivity.

Researchers at the University of Nebraska Medical Center (Omaha, NE, USA) 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. 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.


The researchers 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 swabs reduced the false-negative rate and detected SARS-CoV-2 at a 10-times lower concentration. The most sensitive test currently used 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.

"Using nanoscale fibers, instead of micro scale fibers, we have created extremely absorptive swabs that can detect SARS-CoV-2 at very low concentrations and reduce false negative tests," said Jingwei Xie, PhD, associate professor, UNMC Department of Surgery-Transplant and Mary & Dick Holland Regenerative Medicine Program. "We have been investigating the use of these materials and noting their remarkable absorptive properties and our ability to control their shape, and we thought to repurpose them as swabs."


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University of Nebraska Medical Center