The market for Point Of Care (POC) diagnostics is currently dominated by blood and urine samples that routinely require examination in a laboratory. This can be time consuming and expensive and for some medical conditions more than one test may be required to asses a patient over time. Blood and urine tests are often used by medical practitioners to determine a patient’s present or changing physiological and biochemical state. Such tests may measure a biomarker of disease, pharmaceutical drug effectiveness, and basic physiological indicators such as organ function. Both blood and urine tests are also used in toxicity examinations to detect drug abuse.
Scientists at Swansea University’s Centre for NanoHealth (CNH) have designed an innovative biosensor for the assessment of an increased cancer risk in patients. The biosensors are based on silicon nanowire and graphene platforms which have an intrinsically high surface to volume ratio – which results in higher sensitivities. Graphene is grown onto a silicon carbide substrate under high temperatures and a low pressure. The graphene devices are then patterned using semiconductor processing techniques, before a number of bioreceptor molecules are attached. These receptors are able to bind to, or target, a specific molecule present in blood, saliva or urine. The molecule, 8-hydroxydeoxyguanosine (8-OHdG), is produced when DNA is damaged and, in raised levels, has been linked to an increased risk of developing several cancers. 8-OHdG is present at very low concentrations in urine, so is very difficult to detect using conventional detection methods. The graphene biosensor can detect 8-OHdG concentrations as low as 0.1 ng/mL, which is almost five times more sensitive than other bioassay tests. Research to date suggests that the graphene biosensor is also considerably faster at detecting the target molecules, completing a full sample analysis within minutes.
This research highlights the potential of graphene biosensors to diagnose and monitor a whole range of diseases and conditions, as well as detecting a number of different biomarkers. The commercialisation of the graphene biosensor opens up the possibility of a rapid, POC diagnostic tool for patients.
A UK patent has been filed by Swansea University under GB2010/001231
Inventor: Owen Guy