Mixed Zwitterion-Based Self-Assembled Monolayer Interface for Impedimetric Glycomic Analyses of Human IgG Samples in an Array Format

An impedimetric lectin biosensor for the detection of changes in the glycan structure of antibodies isolated from human serum is here correlated with the progression of rheumatoid arthritis (RA). The biosensor was built up from a mixed self-assembled monolayer (SAM) on gold consisting of two different thiolated zwitterionic derivatives, carboxybetaine and sulfobetaine, to resist nonspecific interactions. The carboxyl-terminated one was applied also for the covalent immobilization of lectin Ricinus communis agglutinin I (RCA-I). The process of building a bioreceptive layer was optimized and characterized using a diverse range of techniques. Impedimetric assays were integrated on a chip consisting of eight gold working electrodes, which is an important step toward the achievement of a moderate level of multiplexing for the analysis of human serum samples. At the end, the results obtained by the impedimetric analysis of immunoglobulins G (IgGs) isolated from serum samples were compared with those of two othe...