Cancer detector: Graphene solution

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  • Published: Oct 1, 2014
  • Author: David Bradley
  • Channels: X-ray Spectrometry
thumbnail image: Cancer detector: Graphene solution

Better than exfoliation

Illustration of an epitaxial graphene channel biosensor for detection of targeted 8-hydroxydeoxyguanosine Credit Guy et al, Centre for Nanohealth, Swansea University/Institute of Physics

Researchers have used X-ray photoelectron spectroscopy and Raman spectroscopy to confirm that bioreceptor molecules attached to a graphene biosensor exposed to cancer biomarkers can reveal the presence of these markers and so might be used as a cancer detector. The team from the University of Swansea have developed a viable biosensor by patterning the carbon material graphene over a large substrate area using a growth method rather than the more conventional exfoliation technique of stripping away layers from graphite to obtain the monolayers. In their approach, they were able to grow graphene on a silicon carbide substrate at extremely high temperature but low pressure. Standard semiconductor patterning methods were used to process the surface of the graphene to form micro channels which were then functionalised with phenylamine using a generic electrochemical method to allow attachment of a number of bioreceptor molecules . The team reports details of the development of this biosensor in the journal 2D Materials published by the UK's Institute of Physics. They provide data from their XPS and Raman spectroscopy used to confirm that they were able to attach the bioreceptor molecules to the fabricated graphene biosensor.

My dear ELISA!

The receptors on the device can bind to specific biological target molecules that might be found in a blood, saliva or urine sample from a patient suspected of having a particular disease. In the present case, the molecule, 8-hydroxydeoxyguanosine (8-OHdG), is the target tested. This compound is formed when DNA undergoes damaged. Its presence in the blood at elevated levels can be indicative of an increased risk for various forms of cancer. It is, however, typically present at only very low concentrations in urine, so is difficult to detect using conventional enzyme-linked immunosorbent assays (ELISAs). The new graphene-based sensor is five times as sensitive as conventional assays currently used for detecting other compounds in the clinic for . Moreover, it works quickly, giving a reading within a few minutes, thus offering the possibility of rapid, "point-of-care" diagnostics for pressured clinicians and worried patients.

The team reports that when 8-OHdG is attached to the bioreceptor molecules on the sensor, there is a notable difference in the channel resistance exhibited by the graphene, which can be recorded easily. Their tests showed that the graphene sensor was capable of detecting 8-OHdG concentrations as low as 0.1 nanograms per millilitre (0.35 nanomolar), which is almost five times as sensitive as ELISA. The team suggests that substituting the 8-OHdG receptor for receptors associated with other diseases would allow the same biosensors to be used to detect a range of illnesses.

Scalable sensor

Team member Owen Guy explains their success: "Graphene has superb electronic transport properties and has an intrinsically high surface-to-volume ratio, which make it an ideal material for fabricating biosensors," he says. "Now that we've created the first proof of concept biosensor using epitaxial graphene, we will look to investigate a range of different biomarkers associated with different diseases and conditions, as well as detecting a number of different biomarkers on the same chip." In addition, the team describes their approach as "scalable, reliable and capable of providing a rapid, quantitative, label-free assessment of biomarkers at nanomolar concentrations in analyte solutions."

The work was carried out by Guy and Swansea colleagues Zahri Tehrani , Gregory Burwell, Mohd Azmi, Ambroise Castaing, Robert Rickman, Jamal Almarashi, Peter Dunstan and Shareen Doak and Ali Akbar Miran Beigi of the Research Institute of Petroleum Industry, Tehran, Iran.

"We are now working on developing scale up processes for fabricating graphene sensors in much higher volumes," Guy told SpectroscopyNOW. "We're also very interested in adapting the graphene sensor platform for a number of other disease biomarkers and for simultaneous detection of a number of biomarkers on the same chip. This is very challenging, but could ultimately result in much more informative Point of Care, rapid diagnostics."

Related Links

2D Mater, 2014, 1, 025004: "Generic epitaxial graphene biosensors for ultrasensitive detection of cancer risk biomarker"

Article by David Bradley

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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