Researchers from the University of Swansea (Swansea, UK) have developed a graphene-based biosensor to detect the cancer biomarker 8-hydroxydeoyguanosine.
On September 19th 2014, in the journal 2D Materials, researchers from the University of Swansea (Swansea, UK) presented a graphene biosensor capable of detecting the cancer biomarker 8-hydroxydeoyguanosine (8-OHdG). The biosensor has been shown to be extremely sensitive; it is five-times more sensitive than bioassay tests currently used, moreover it also showed potential as a rapid point-of-care diagnostic tool as it was able to provide results in a matter of minutes.
The researchers grew graphene onto a silicon carbide substrate under extremely high temperatures and low pressure to form the basis of the biosensor. This technique was required to create a patterned graphene device with a large substrate area as the traditional exfoliation technique, where layers of graphene are stripped from graphite, was not adequate.
8-OHdG is produced when DNA is damaged, and, in elevated levels, it has been linked to an increase in the risk of developing several cancers. The cancer biomarker is difficult to detect using ELISAs, as it is present at very low concentrations in urine.
After the researchers formed the basis of the biosensors, the graphene devices were patterned. To pattern the graphene device, first semiconductor processing techniques were employed. Next a number of bioreceptor molecules, which could bind to, or target, a specific molecule present in blood, saliva or urine, were attached.
Researchers used x-ray photoelectron spectroscopy and Raman spectroscopy to confirm that bioreceptor molecules had attached to the graphene biosensor; once they had confirmation, the biosensor was exposed to varying concentrations of 8-OHdG. A notable difference in graphene channel resistance was observed when 8-OHdG was attached to the bioreceptor molecules on the sensor. The device was so sensitive that 0.1 ng ml-1 levels of 8-OHdG could be detected.
Potentially, biosensors could be used to detect a whole range of diseases as it is relatively simple to attach the specific receptor molecules onto the graphene surface. Owen Guy, co-author of the study, stated, “Graphene has superb electronic transport properties and has an intrinsically high surface-to-volume ratio, which make it an ideal material for fabricating biosensors. 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.”
Sources: Graphene sensor tracks down cancer biomarkers; Tehrani Z, Burwell G, Mohd Azmin MA, et al. Generic epitaxial graphene biosensors for ultrasensitive detection of cancer risk biomarker. 2D Mater. 1(2), 025004 (2014).