Towards a blocking-free electrochemical immunosensing strategy for anti-transglutaminase antibodies using screen-printed electrodes

• A blocking-free one-step assay using screen-printed electrodes was developed.
• Detection of anti-transglutaminase IgA antibodies was performed in 80 min.
• A linear range from 3 to 40 U mL− 1 was obtained using human serum controls.
• A limit of detection of 2.7 U mL− 1 was estimated.
• The immunosensor was stable at least for 1 month stored at 4 °C.

A blocking-free one-step immunosensing strategy using 8-channel screen-printed arrays for the detection of anti-transglutaminase IgA antibodies, celiac disease biomarkers, was developed. A simple but novel immobilization approach to efficiently modify the surface of screen-printed electrodes with a recognition element was employed in order to minimize the non-specific adsorption on the electrode surface, and the optimization of a methodology without a blocking step was carried out. After the functionalization of the electrode surface with tissue-transglutaminase, two different immunoassays, using multi-step and one-step strategies, were optimized. Serum controls from a commercial ELISA kit, anti-human IgA labelled with biotin and streptavidin labelled with CdSe/ZnS quantum dots were employed as bioreagents for the immunoassay. Screen-printed arrays were used as the solid support for the immunosensor and the detection of Cd(II) was performed in situ by anodic stripping voltammetry after an acid attack of the QDs. The electrochemical response from Cd(II) was correlated with the anti-transglutaminase IgA antibody concentration. The analytical characteristics obtained for the multi-step and one-step electrochemical immunosensors allow discrimination between positive and negative serum controls, establishing this biosensor as a useful tool for the determination of celiac disease biomarkers.

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