Graphene Field-Effect Transistor-Based Biosensors: From Detection Mechanisms to Ultrasensitive Sensors - NEWS

The use of gold standards for the detection of various analytes, ranging from the food industry to medical diagnostics, remains prevalent today due to their high accuracy and reliability. Although there is a growing trend towards replacing such methods with considerably simpler and more user-friendly tools, such as miniaturized sensors or point-of-care devices, very few of these solutions have been adopted in practice. One of the reasons for this is the use of advanced materials that provide enhanced sensitivity, while their scalability to large-scale production remains a significant challenge. This is also the case with graphene, a two-dimensional carbon-based material whose exceptional electrical and mechanical properties place it among the most advanced materials available today, yet its uniform and reproducible large-scale production remains a major challenge. In this seminar, several solutions based on graphene field-effect transistors (GFETs) will be presented, as these platforms are well suited for the development of miniaturized biosensors with very high sensitivity, accuracy, and rapid response. The development of a biosensor for the detection of the mycotoxin ochratoxin A in wine using a GFET chip based on monolayer graphene will be presented, along with a low-cost GFET fabrication technology aimed at developing a biosensor for the detection of the cardiac biomarker NT-proBNP, as well as a GFET immunosensor for the detection of the birch pollen allergen Bet v 1. All three studies are based on GFET devices fabricated using graphene materials (either monolayer CVD graphene or graphene oxide flakes), whose surfaces are functionalized with bioreceptors (aptamers or antibodies) to achieve biosensor specificity. In the case of aptasensors, understanding the interaction between the graphene lattice and the aptamer is particularly important, since the GFET biosensor signal is generated by changes in the local charge distribution in the vicinity of the graphene channel, resulting in changes in the electrical characteristics of the GFET. By examining changes in the transfer characteristics of the GFET, it is possible to infer how the negatively charged aptamer interacts with graphene and thereby more precisely determine the nature of the signal generated during detection. By elucidating the detection mechanism of GFET aptasensors, biosensors employing aptamers as recognition receptors, a better understanding of label-free detection using these devices can be achieved, thereby making the scaling-up of this technology more feasible in principle.