Researchers at the University of Illinois have developed a paper-based electrochemical diagnostic test for COVID-19 that can provide a result in just five minutes. The inexpensive test relies on the conductive properties of graphene and gold, and contains gold nanoparticles covered in sensitive nucleic acid probes that can bind to RNA from the SARS-CoV-2 virus. The presence of viral RNA changes the electrical readout from the sensor, indicating a positive result.
While news of effective vaccines is very welcome during the ongoing COVID-19 pandemic, achieving widespread immunity will take a while, and measures such as social distance and mask wearing will be with us for some time to come. A key measure in tracking and controlling COVID-19 transmission is comprehensive testing, but many countries have struggled with this and the current gold-standard PCR tests are time and labor intensive.
Researchers are rapidly redeploying other testing methods to aid in the pandemic response, and this latest test uses a paper-based electrochemical method to achieve viral detection in as little as five minutes. “Currently, we are experiencing a once-in-a-century life-changing event,” said Maha Alafeef, a researcher involved in the study, in a press release. “We are responding to this global need from a holistic approach by developing multidisciplinary tools for early detection and diagnosis and treatment for SARS-CoV-2.”
The new test consists of filter paper covered in a layer of conductive graphene. “The discovery of graphene opened up a new era of sensor development due to its properties,” added Alafeef. “Graphene exhibits unique mechanical and electrochemical properties that make it ideal for the development of sensitive electrochemical sensors.”
The sensor also contains gold nanoparticles coated with sensitive oligonucleotide probes specific for two regions of a gene present in SARS-CoV-2. If viral RNA is present in a sample, it will bind to the probes, changing the electrical properties of the sensor and resulting in an increase in the output signal. So far, the researchers have tested the device with samples spiked with the virus, and found that the sensor could rapidly detect it and also provide an indication of viral load, suggesting that it could indicate disease progress.
It’s not clear what the manufacturing costs of this kind of test would be, considering it relies on graphene, which is not trivial to mass produce.