Could a nano-biochip made of graphene detect the cancer biomarker 8–hydroxydeoxyguanosine (8–OHdG), faster and more sensitively than conventional enzyme-linked immunosorbent assays (ELISA)? Researchers from the University of Swansea, UK, claim the answer is yes.
8-OHdG is a DNA adduct produced by oxidative stress that has been linked to bladder, lung, and prostate cancer. It can be detected using ELISA but the assay isn’t perfect as it can’t always identify the low levels of the biomarker that may be present in the early stages of disease or in a urine sample. In comparison, the Swansea team say their graphene biochip can detect the biomarker at concentrations five times lower than ELISA, as well as being easier and faster; apparently testing can be carried out in minutes. “We were surprised at how sensitive our graphene sensor is,” says co-author Owen Guy, professor of engineering at Swansea University, “but with improved design, we may be able to achieve even higher sensitivities.”
Since it was first made in the lab in 2004, the unique properties of graphene have made it a popular substance within the research community. The authors describe graphene as a “disruptive technology” in next-generation electronics and healthcare diagnostics since its electronic properties and high surface-to-volume ratio allow for high sensitivity. For the biosensor, the researchers created functionalized graphene channels by coating them in monoclonal antibodies (using spectroscopy to check they had bound correctly), that then enabled the channels to selectively bind 8-OHdG. Changes in the electrical conductivity of the biochip were then measured to test for the presence of the biomarker (1).
Owen adds that once the device has been validated through further testing, it could also be used to test for other cancers or diseases, simply by changing the antibody that’s attached. He says, “We’re now working on developing scale-up processes for fabricating graphene sensors in much higher volumes. We are also very interested in adapting the graphene sensor platform for simultaneous detection of a number of biomarkers on the same chip. This is very challenging, but could result in much more informative diagnostics.”
Newsletters
Receive the latest pathology news, personalities, education, and career development – weekly to your inbox.
References
- Z. Tehrani et al., “Generic Epitaxial Graphene Biosensors for Ultrasensitive Detection of Cancer Risk Biomarker”, 2D Materials, 1 (2014).