Abstract: A common feature seen in different types of cancer, namely in carcinomas, is the alteration in post-translational modifications of proteins, particularly in protein glycosylation. Due to increased or decreased expression of specific enzymes participating in glycosylation of proteins, different glycan structures are formed, which are typical of tumoral cells. When the respective glycoproteins are secreted into the blood stream, these aberrant structures can be used as valuable cancer biomarkers, since they are not synthesized by normal cells. Glycan structures are efficiently and selectively detected by lectins, which are proteins of natural origin with high affinity for a unique or a very small group of glycan epitopes. Lectins are used for glycan detection as antibodies are used for protein recognition. Lectin biosensors are attractive devices for the detection of cancer-associated glycobiomarkers in serum since they combine the advantageous aspects of biosensors (portability, easy use in point-of-care analysis, low sample requirement) with the high selectivity of lectin biorecognition. This work presents three lectin-based impedimetric biosensors for the selective detection of specific aberrant cancer-associated O-glycans, namely STn, Tn and T antigens, which are well- established pan-carcinoma biomarkers. For these three biosensors, Sambucus nigra agglutinin, Vicia villosa agglutinin and Arachis hypogeae agglutinin were used as biorecognition elements, with specificity for STn, Tn and T antigens, respectively.

Keywords: Cancer, Glycobiomarkers, Truncated O-glycans, Biosensor, Lectins, Electrochemical impedance spectroscopy, Screen printed electrodes.

.__________________________________________________________________________________________