LAUSR

In this work, 1-200 µL polypropylene micropipette tips were used as the platform for performing immunoassays after converting their inner surface on a capture zone for the analyte of interest. We have used a micropipette-tip immunoelectroanalytical platform for the detection of anti-tissue transglutaminase (IgA), the main biomarker for the celiac disease. Modification of the tip wall with poly-L-lysine allowed adsorption of tissue transglutaminase (tTG), which will capture later anti-tTG (IgA) antibodies developed in celiac people. A sandwich-type format was followed, incubating simultaneously the analyte and the detection antibody, labeled with horseradish peroxidase. With this new application for an extremely common lab material, we can perform quantitative analysis by dispensing the liquid into a low-cost and miniaturized staple-based paper electrochemical platform., The analytical signal was the reduction of the enzymatically-oxidized substrate, recorded chronoamperometrically (i-t curve). The intensity of the current obtained at a fixed time after application of the cathodic potential followed a linear relationship with anti-tTG (IgA) concentration. The relative standard deviation (RSD) obtained for immunoassays performed in different tips, indicates the adequate precision of this new methodology, very promising for decentralized analysis. Negative and positive controls produced results that were in accordance with those obtained with spectrophotometric ELISAs.