Highly sensitive covalently functionalised integrated silicon nanowire biosensor devices for detection of cancer risk biomarker

• We present an ultra-sensitive antibody-functionalised SiNW sensor chip integrated with a readout device for detection of the biomarker 8-OHdG.
• Functionalisation of SiNW was achieved using an electrochemical diazotization method for nitro-phenyl attachment to silicon surfaces.
• The reduction process, converting the nitro group to an amine was achieved rapidly, under production friendly conditions.
• The advantage of this functionalisation method lies in its simplicity, avoidance of harsh oxidation chemistry and speed of reaction.
• Rapid detection of 8-OHdG concentrations as low as 1 ng/ml (3.5 nM) has been demonstrated.

In this article we present ultra-sensitive, silicon nanowire (SiNW)-based biosensor devices for the detection of disease biomarkers. An electrochemically induced functionalisation method has been employed to graft antibodies targeted against the prostate cancer risk biomarker 8-hydroxydeoxyguanosine (8-OHdG) to SiNW surfaces. The antibody-functionalised SiNW sensor has been used to detect binding of the 8-OHdG biomarker to the SiNW surface within seconds of exposure. Detection of 8-OHdG concentrations as low as 1 ng/ml (3.5 nM) has been demonstrated. The active device has been bonded to a disposable printed circuit which can be inserted into an electronic readout system as part of an integrated Point of Care (POC) diagnostic. The speed, sensitivity and ease of detection of biomarkers using SiNW sensors render them ideal for eventual POC diagnostics.