Researchers at the University of Illinois Grainger College of Engineering have developed an ultrasensitive test using a paper-based electrochemical sensor that can detect Covid-19 within five minutes.
The researchers employed the use of graphene biosensor, which is adaptable to other viruses, as per a study published in the journal ACS Nano.
There’s need for a smart testing policy for Covid-19
The team, led by professor Dipanjan Pan and Maha Alafeef, a bioengineering graduate student from the University of Illinois Grainger, developed the ultrasensitive test.
“Currently, we are experiencing a once-in-a-century life-changing event. 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,” said Alafeef.
He added: “The discovery of graphene opened up a new era of sensor development due to its properties. Graphene exhibits unique mechanical and electrochemical properties that make it ideal for the development of sensitive electrochemical sensors.”
Portable Covid-19 test that gives results in 30 minutes
According to the research, there are two components to this biosensor: a platform to measure an electrical read-out and probes to detect the presence of viral RNA.
To create the platform, researchers first coated filter paper with a layer of graphene nanoplatelets to create a conductive film. Then, they placed a gold electrode with a predefined design on top of the graphene as a contact pad for electrical readout.
Ensuring reliability
The team designed antisense oligonucleotide (ASOs) probes to target two regions of the N-gene. Targeting two regions ensures the reliability of the sensor in case one region undergoes gene mutation.
Furthermore, gold nanoparticles (AuNP) are capped with these single-stranded nucleic acids (ssDNA), which represents an ultra-sensitive sensing probe for the SARS-CoV-2 RNA.
The team conducted the test on their sensor by using Covid-19 positive and negative samples. The sensor showed a significant increase in the voltage of positive samples compared to the negative ones and confirmed the presence of viral genetic material in less than five minutes.
Notably, the sensor was able to differentiate viral RNA loads in these samples.
“Viral load is an important quantitative indicator of the progress of infection and a challenge to measure using existing diagnostic methods”, stated the researchers.
The sensor can be applied to various uses due to its portability and low cost. The sensor, when integrated with microcontrollers and LED screens or with a smartphone via Bluetooth or Wi-Fi, could be used at the point-of-care in a doctor’s office or even at home, the researchers noted.