Using graphene for rapid diagnostic tests

A project to develop rapid diagnostic tests for infections that uses the Nobel-prizewinning substance "graphene" is underway at the Cambridgeshire-based company Paragraf. They've pioneered a way to make the carbon-based material at scale and consistently. They plan to use the technique to produce mobile-phone-sized chemical sensor devices that can pick up, in a matter of minutes, markers of disease in minute quantities of blood. Malcolm Stewart is Paragraf's Business Development Director...

Malcolm - Well, we'll take a sample of say blood, which contains lots of different biomarkers for diseases and conditions. Put it onto a Silicon chip-type device made of graphene, which is tuned to look for a particular chemical or protein or something, which tells the clinician that you've got a condition. And within a couple of minutes, from just a drop or two of blood, we can tell perhaps if you have an infection or maybe even a more serious disease.

Chris - What's special about graphene here?

Malcolm - Well, graphene is a really interesting material. A single layer of carbon atoms in a lattice shaped like honeycombs. And it's incredibly conductive and that's one of the properties that makes it ideal for diagnostics. We want to see very small quantities of these chemicals in the blood. And if you've got a very conductive material like graphene, you'll be able to see them more easily.

Chris - How do you come up with the sensors in the first place that you're gonna stick on that sheet of graphene that will find those biomarkers?

Malcolm - So what we do is we take different chemicals and join them together and at the top of that little stack is something like an antibody. And the antibody is tuned to look for a bacterium or a virus like COVID, for example, , and it, when in contact with the blood or the saliva that we put onto it, will find that protein or the virus in the sample.

Chris - And when it binds, that changes the electrical behavior of the graphene in a way that you can detect is the sort of chemical signature or electrical signature. This is bound, therefore this amount is there of that thing.

Malcolm - Yeah, exactly. So, when a binding event happens, we get a change in the electrical property, which we can measure very easily. And as that change accumulates, we can then tell how much of that chemical or biomarkers in the sample.

Chris - Now you said minute quantities. How minute are we talking about? Because in the lab that I helped to run, we are talking about a finger full of blood - big, big volumes. There's also been a company that now is somewhat infamous that made their name saying they were gonna analyze tiny quantities of blood. They went down the tubes, it was all hocus pocus. Can you really do this with tiny quantities of blood?

Malcolm - Well, we think we can. And it's about tuning the chemistry and taking the time to get all the data to show that we can. We'll do studies in real humans, in the next few years to show that we can, and we compare ourselves to devices, which are currently being used in hospitals to make sure that our performance is as good as clinicians require.

Chris - And presumably this has got lots of applications, not just in this country, but worldwide. Because if it is small, it is cheap and it's very sensitive but easy to manufacture, you could presumably roll this out to third world, many, many places with resource poor settings.

Malcolm - Very much so. And our hope is to get into helping low and medium income countries deal with simple infections, like COVID, through to much more complex tropical disease type infections, which for example, spread very rapidly. So yes, very much we have it in our sights to make sure this is a product that can be useful worldwide.