Graphene-based lectin biosensor for ultrasensitive detection of glycan structures applicable in early diagnostics

It is a well-known fact that various pathological conditions result in an increased concentration of specific substances (biomarkers) in blood or urine. Some biomarkers may carry on their surfaces characteristic saccharide structures (glycans), which may have a different structure comparing to normal (healthy) physiological condition. This means, that glycan profiling can distinguish between healthy and sick individuals and, in some cases, even determine the stage of the disease. Glycoprofiling of biological samples is relatively demanding and often requires complex instrumentation. In addition, many of currently used methods involve labelling or fragmentation of target molecules, which can eventually influence whole analysis. Contrary to this, electrochemical methods provide very sensitive, rapid and simple analysis of intact glycoproteins in real samples, without the need of labelling, which makes them a strong tool for biosensor construction and optimization. Lectins are carbohydrate-binding proteins able to recognize free, mono- and oligosaccharides or even whole cells. Therefore, lectin biosensors are very promising candidates for glycan analyses and they can be used even in case when the target is unknown. Nowadays, the term of biosensors is inextricably linked with the concept of nanotechnology. Since 2004, graphene attracts worldwide attention in the field of (electro)biosensing thanks to its impressive properties. In our work we have demonstrated that graphene-materials are prospective tool for fabrication of lectin-based biosensor allowing different way of lectin immobilization. Moreover, prepared biosensor is able to recognize femtomolar concentration of analyte. Therefore there is no doubt, that electrochemical biosensors, which combine specific qualities of lectins and unique features of graphene materials, are innovative approach in glycoprofiling, yet this concept is still rare.