Z. Tehrani

Generic epitaxial graphene biosensors for ultrasensitive detection of cancer risk biomarker

A generic electrochemical method of ?bioreceptor? antibody attachment to phenyl amine functionalized graphitic surfaces is demonstrated. Micro-channels of chemically modified multi-layer epitaxial graphene (MLEG) have been used to provide a repeatable and reliable response to nano-molar (nM) concentrations of the cancer risk (oxidative stress) biomarker 8-hydroxydeoxyguanosine (8-OHdG). X-ray photoelectron spectroscopy, Raman spectroscopy are used to characterize the functionalized MLEG. Confocal fluorescence microscopy using fluorescent-labelled antibodies indicates that the anti-8-OHdG antibody selectively binds to the phenyl amine-functionalized MLEG?s channel. Current?voltage measurements on functionalized channels showed repeatable current responses from antibody?biomarker binding events. This technique is scalable, reliable, and capable of providing a rapid, quantitative, label-free assessment of biomarkers at nano-molar (<20 nM) concentrations in analyte solutions. The sensitivity of the sensor device was investigated using varying concentrations of 8-OHdG, with changes in the sensor?s channel resistance observed upon exposure to 8-OHdG. Detection of 8-OHdG concentrations as low as 0.1 ng ml?1 (0.35 nM) has been demonstrated. This is five times more sensitive than reported enzyme linked immunosorbent assay tests (0.5 ng ml?1).

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

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.

Detection of monoclonal antibodies using chemically modified graphite substrates

This paper presents a novel sensor device based on chemically modified Highly Ordered Pyrolytic Graphite (HOPG). Biosensor diagnostics based on bio-functionalised semiconductor devices are an important development in ultrasensitive sensors for early detection of disease biomarkers. Electrochemical devices using chemically modified graphite (CMG) channels are excellent candidates for nano-biosensors [1]. By attaching aniline to HOPG, via coupling with an aryl diazonium salt, the amino group of the aniline molecule has been used to graft antibodies - (1) targeted against beta-actin and (2) targeted against 8-hydroxydeoxyguanosine (8-OHdG) - onto the HOPG surface. Antibody attachment to graphitic surfaces has been verified using Laser Scanning Confocal Microscopy (LSCM) to detect attached quantum-dot labeled antibodies. Furthermore, the current-voltage characteristics of virgin and chemically modified HOPG surfaces have been used to detect the presence of antibodies at nM concentrations.

Graphene Nano-Biosensors for Detection of Cancer Risk

Biosensor diagnostics based on bio-functionalized semiconductor devices are an important development in ultrasensitive sensors for early detection of disease biomarkers. Electrochemical devices using chemically modified graphene (CMG) channels are excellent candidates for nanobiosensors. This paper presents the development of novel antibody functionalized epitaxial graphene devices for bio-sensing applications. Epitaxial graphene has been grown on silicon carbide (SiC) substrates under high vacuum and high temperature conditions (1200 – 1700°C). A generic electrochemical surface functionalisation chemistry, which can be used to attach a variety of “bio-receptors” to graphitic surfaces, has been developed. The attached bio-receptors are capable of specific and selective interaction with disease biomarkers. When a target biomarker molecule interacts with the “bio-receptor” functionalized surface, the charge density at that surface is affected. This change can be detected as an electrical signal from the biosensor, enabling highly sensitive (nM) detection of biomarker analytes. This paper reports the fabrication of graphene channel sensors for detection of disease biomarkers.

Fabrication of ultrasensitive graphene nanobiosensors

The development of miniaturised systems for detection of disease biomarkers, at clinically relevant concentrations in biological samples, is key in the early diagnosis and monitoring of diseases. This paper presents the development of novel antibody functionalized epitaxial graphene devices for bio-sensing applications. Epitaxial graphene has been grown on silicon carbide (SiC) substrates under high vacuum and high temperature conditions (1200 – 1700°C). A generic electrochemical surface functionalisation chemistry, which can be used to attach a variety of “bio-receptors” to graphitic surfaces, has been developed. The attached bio-receptors are capable of specific and selective interaction with disease biomarkers. When a target biomarker molecule interacts with the “bio-receptor” functionalised surface, the charge density at that surface is affected. This change can be detected as an electrical signal from the biosensor, enabling highly sensitive detection of biomarker analytes.

Three-Dimensional–Printed Laboratory-on-a-Chip With Microelectronics and Silicon Integration

Abstract In this research, an integrated three-dimensional (3D)–printed laboratory-on-a-chip system was developed based on integrating conventional silicon biosensing systems with silver screen–printed electronics. It was discovered that by integrating 220-&mgr;m width microchannels, fabricated using 3D-printed polymers, it would offer a means for the development of a microfluidic device with the further possibility for electrically integrating different elements through depositing screen-printed silver contacts. The objective was to achieve low resistance and high reliability with low cost for manufacturing 3D-printed point-of-care diagnostic devices.

Integration of Silicon and Printed Electronics for Rapid Diagnostic Disease Biosensing

AbstractDuring this research, we developed a printed point-of-care device that was integrated with a biosensing silicon sensor. This resulted in the detection of a specific biomarker, which indicates the presence of a series of common diseases. The selective detection of biomarkers is an important c

Integrated Point-of-Care SiNW biosensors

A SiNW sensor consisting of a SiNW, functionalised with a “bioreceptor” which can interact selectively with a target biomarker, has been developed. By attaching aniline to a SiNW, via coupling with an aryl diazonium salt, the amino group of the aniline molecule has been used to graft antibodies - targeted against 8-hydroxydeoxyguanosine (8-OHdG) - onto the SiNW surface. Antibody attachment to SiNW surfaces has been verified using Laser Scanning Confocal Microscopy (LSCM) to detect quantum-dot labelled antibodies bound to the SiNW surface. The current-voltage (I-V) characteristics of the silicon nanowire devices show an increase in resistivity upon chemical functionalization with aniline. A decrease in resistivity is seen on binding of the bioreceptor antibody. The antibody-functionalised SiNW sensor has been used to detect binding of the 8-OHdG biomarker to the SiNW surface within seconds of exposure. SiNW devices have been bonded to a disposable “bio-smartcard” and subsequently slotted into an electronic readout device. This system has been specifically developed for Point-of-Care (POC) use.