Staple‐Based Paper Electrochemical Platform for Celiac Disease Diagnosis

A staple‐based electrochemical platform is proposed for the first time as a simple and low‐cost detection system for paper‐based devices. The system, which incorporates small and disposable stainless‐steel staples as electrodes, is combined with a paper strip. The staple acting as the working electrode is modified with carbon ink. The platform was carefully optimized with ferrocene carboxylic acid. As a proof‐of‐concept, it was employed for the enzymatic [horseradish peroxidase (HRP)‐based] immunoelectroanalytical detection of human tissue anti‐transglutaminase (anti‐tTG), which is a biomarker for celiac disease diagnosis. The intensity of the current from the electrochemical reduction of 3,3′,5,5′‐tetramethylbenzidine (an HRP substrate) was recorded chronoamperometrically at −0.2 V in different paper areas. A linear relationship between the current measured at 30 s and the logarithm of the concentration of anti‐tTG in the range comprised between 3 and 100 U mL−1 was obtained. Negative and positive controls produced expected values. Results demonstrated that the paper/staple combined platform is very convenient for the detection of electroactive analytes and other compounds that can be determined indirectly in bioassays. Staples diagnose celiac disease: A staple‐based electrochemical platform is proposed for the first time as a simple and low‐cost detection system for paper‐based devices. As a proof‐of‐concept, it is employed for the detection, through an enzymatic immunoassay, of human tissue anti‐transglutaminase, an analyte related to the celiac disease. The strategy is based on the use of a three‐electrode platform consisting of easy‐accessible mass‐produced stainless‐steel staples. In the case of the working electrode, the inner surface is modified with carbon ink to favor electron transfer.