A Nose for Cancer

The correlation between early diagnosis and better clinical outcomes for patients with lung cancer is well established, but developing an appropriate detection system is easier said than done (1). Several commercially available breath-based detectors have emerged in recent years, yet uptake in the clinic has been slow – hampered by poor sensitivity. Now, an international team based out of the University of Exeter (UoE), UK, is trialing a new system – a multi-layered, patterned graphene sheet that is capable of detecting changes in surface binding.

Evgeniya Kovalska, a postdoctoral research fellow in engineering at the UoE, and the first author of a paper that describes the technique (2), says that the graphene-based tool was the next logical step for her research group. “We’d already been exploring the applications of graphene, so the infrastructure to synthesize and develop our device was already in place,” she explains. “Graphene has a range of surface chemical properties that can be used to modify its structure and make it highly responsive to detecting different biomarkers.”

Using a technique called chemical vapor deposition (CVD), the team were able to “grow” a patterned graphene film on a canvas made of nickel, before the entire platform was transferred onto a plastic substrate. “Patterned graphene greatly increases the surface area, which improves our tool’s ability to act as a surface detector,” says Ben Hogan, a doctoral researcher working on the project. “Our rationale was that, by combining this with graphene’s excellent electro-conductive properties, we could greatly increase the sensitivity of the electrodes.”

But given the scarcity of biomarkers in any given breath sample, the researchers had plenty of tweaking to do. “You’re looking at samples that are 99 percent water; trying to detect really minute changes in that other 1 percent is... tricky,” says Hogan. “You want to make the tool as hydrophobic as possible to avoid interaction in the water,” says Hogan. “At the same time, you want to increase its interaction with specific molecules of interest.”

Following in the footsteps of other groups, the team focused on volatile organic compounds (VOCs). “We’ve only looked at a few biomarkers so far,” says Hogan. “But they are well representative of a wider sample, so we are confident that using a limited number of biomarkers shouldn’t be a major issue.” With further development, the team is optimistic that the tool can be tailored to a wider variety of biomarkers.

And Hogan believes there is scope for further optimization. “We could introduce additional layers to the structure,” he says. “Or we could add new chemical groups to the surface, which could change its interactions with specific molecules.”  Indeed, the continued goal is to push the limits of detection. “Lower concentrations would, in principle, allow us to diagnose the condition earlier,” he says. “If we can do that, then it would obviously be of great benefit to the patient.”

The patient-centric philosophy hinted at by Hogan is more than just words – it’s perhaps best represented by the team’s bold decision to reject patenting the device in favor of publishing the work in an open access journal. “Ultimately, we’re not doing this for personal benefit,” says Hogan. “We think it’s much better to get it out there and into the community – and it’s our hope that it is picked up by other groups who will also take it forward.”