Lectins as Biorecognition Elements in Biosensors for Clinical Applications in Cancer

Lectins are proteins or glycoproteins present in a variety of natural organisms. Since the time they were first described, at the end of the nineteenth century, new methods for their extraction and purification have been developed and, in parallel, they have been thoroughly studied. In spite of their great diversity and ubiquity, currently they constitute a group of well-characterized biomolecules. The most attractive feature of lectins is that they recognize and selectively bind to carbohydrate structures and that can be used for particular purposes in the biological and medical areas, for example. Due to their behaviour, lectins have become valuable analytical tools and numerous applications have been reported. Lectin-based analytical techniques allow to detect, extract, characterize and quantify specific glycans or glycoconjugates in diverse samples such as biological fluids. Glycobiology has benefit from this trend and lectins are present in some of the most promising applications, namely the diagnosis and monitoring of several diseases through the detection of their specific glycobiomarkers. One of the most prolific areas is the development of lectin-based biosensors for cancer biomarkers. Some limitations of lectins impair a wider application of these biomolecules as analytical tools, namely the lack of 100% specificity between a lectin and a glycan, in opposition to the unique and exclusive relation between an antigen and the corresponding antibody. This drawback can be problematic in the analysis of complex samples. Future directions may focus on identifying new and more specific carbohydrate ligands or developing multi-lectin tools in which a glycoprofile and not a single glycostructure is monitored.

Keywords: Biomarkers, Biosensors, Cancer, Glycans, Glycoproteins, Lectins, Lectin-based analytical techniques, Point-of-care analysis.