Recruitment of Enzymatic Labels via Glycan-Lectin Interactions for Electrochemical Immunosensing of Anti-dsDNA Antibodies

As a group of antinuclear autoantibodies, anti-dsDNA antibodies (dsDNA-Ab) are of great value as the diagnostic markers for systemic lupus erythematosus (SLE). Taking advantage of the one-step recruitment of enzymatic labels for signal amplification via glycan-lectin interactions, we illustrate herein an electrochemical immunosensor for dsDNA-Ab detection at very low concentration levels. In the presence of alkaline phosphatase (ALP) as the enzymatic label, the immunosensing involves the capture of the dsDNA-Ab targets by the tethered dsDNA antigens, the binding of enzymatic labels to the N-linked glycan chains of the targets via glycan-lectin interactions, and the subsequent enzymatic deposition of silver particles. The glycan-lectin interactions can enable the site-directed, multisite recruitment of the enzymatic labels, showing great promise as an alternative to immunorecognition-mediated recruitment. The enzymatic conversion of l-ascorbic acid 2-phosphate (AAPi) into l-ascorbic acid (AA) brings about the deposition of a high density of silver particles for Ag/AgCl solid-state stripping analysis, conferring the electrochemical immunosensor with a detection limit of 12.6 mIU/mL. Moreover, the electrochemical immunosensor shows high selectivity toward dsDNA-Ab detection, and the results of the immunosensing of the targets in human serum samples correlated well with the chemiluminescent immunoassay-based method. As the recruitment of enzymatic labels via glycan-lectin interactions is site-directed, robust, and easy to use, it holds great potential in the electrochemical immunosensing of anti-dsDNA antibodies at very low concentration levels associated with SLE diagnosis.