A Vicia villosa agglutinin biosensor for cancer-associated Tn antigen

A label-free biosensor for selective detection and discrimination of the cancer-associated Tn antigen was developed by using Vicia villosa agglutinin (VVA) as the recognition element. The VVA biosensor was constructed by immobilizing the lectin on screen-printed gold electrodes. The formation of complexes between VVA and Tn-containing glycoproteins (asialo bovine submaxillary mucin and asialofetuin) were monitored by electrochemical impedance spectroscopy, measuring the impedance increase of the biosensor. The biosensor response was related to the glycoprotein amount applied on the sensor surface and asialofetuin amounts down to 2.5 ng still caused an increase in impedance of 5.9%. Albumin, the most abundant serum protein, did not interfere in the detection of the Tn-glycoproteins up to a concentration of 0.01 mg mL?1. The developed lectin-based biosensor was used to evaluate the Tn-expression in serum samples and allowed to discriminate samples from healthy individuals and patients with different types of carcinomas, where the increased expression of Tn aberrant glycans is well established.