The newly developed graphene biosensor could ultimately help to provide a rapid diagnosis at the point of care. In comparison with other bioassay tests, this sensor was over five times more sensitive. 

Conventionally, graphene is produced using an exfoliation technique in which layers of graphene are stripped from graphite. However for a biosensor, a large substrate area is required in order to produce patterned graphene devices.

The researchers used conditions of low pressure and very high temperatures in order to grow graphene on a substrate of silicon carbide. The graphene devices were then patterned by using methods similar to those used when processing semiconductors. The team then attached antibody bioreceptor molecules that could bind to specific target molecules in urine, saliva or blood.

In order to verify if the bioreceptor molecules were bound to the graphene biosensor, the researchers used Raman spectroscopy and x-ray photoelectron spectroscopy. The biosensor was then exposed to various concentrations of the molecule 8-hydroxydeoxyguanosine (8-OHdG).

When high amounts of DNA damage occur, 8-OHdG is produced which is connected to a high risk of cancer development. Traditional detection tests, such as enzyme-linked immunobsorbant assays (ELISAs), are not capable of detecting the low concentrations of 8-OHdG present in urine.

The graphene sensor had the capability to detect low concentrations of 8-OHdG at a comparatively faster rate. Co-author of the study Dr Owen Guy, Swansea University said: “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.”

The paper has been published in 2D Materials, a journal of IOP Publishing  and can be downloaded from http://iopscience.iop.org/2053-1583/1/2/025004/article 

For more information about the Swansea University Centre for NanoHealth go to http://www.swansea.ac.uk/nanohealth

Picture: Illustration of graphene biosensors