Graphene is a layer of carbon only one atom thick. Since it was first isolated in 2004, it has found applications in strengthening materials, accelerating electronics, and boosting performance in batteries, among others.
It also shows great potential for use in biosensors. These are devices used to detect small concentrations of biomarkers in biological samples, such as blood or saliva. Biomarkers are molecules that suggest the presence of disease.
In a recent review, my colleagues and I looked into the latest research to find the most exciting potential applications of graphene in point-of-care tests. This includes diagnostic tests for SARS-CoV-2, the virus responsible for COVID-19, but also detecting other viruses, bacteria and even cancerous tumours.
It’s early days. The technology still needs to go through clinical trials and processes need to be developed to manufacture these tests at scale. However, in the next five years, graphene could start to play a part in healthcare technology.
A single atom layer
Because graphene is a two-dimensional material, it has a tremendously high surface-to-volume ratio, which makes it very sensitive to changes in its environment. Think of a vast, calm lake. Any tiny pebble that hits the surface creates a ripple that quickly expands across the water.
Similarly, when other substances—even single molecules—hit graphene, they generate small, measurable electrical pulses.
Relying on this phenomenon alone to detect SARS-CoV-2 wouldn’t work. When used as a biosensing layer in electronic devices, graphene is sensitive down to a single molecule. Yet it can’t tell the difference between coronavirus and the flu—the same way the lake would confuse a pebble and a marble.
To solve this, researchers have developed chemically modified graphene, coating it with antibodies that bind specifically to SARS-CoV-2. When the virus reaches the sensor and attaches to the antibody, it triggers an electrical signal through the thin graphene layer.
SARS-CoV-2 carries all its genetic information in a strand of RNA, which is often used in detection processes like a polymerase chain reaction (PCR). A PCR device amplifies the amount of RNA in a saliva sample until it becomes detectable under a microscope.
But this process is time consuming, requires expensive equipment and very specific and expensive reagents—substances used in the labelling and amplification process, or in the preparation of the sample.
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Post by Amanda Scott, NA CEO. Follow her on twitter @tantriclens
Thanks to Heinz V. Hoenen. Follow him on twitter: @HeinzVHoenen