Electrochemical Lateral Flow Devices: Towards Rapid Immunomagnetic Assays

Paper has been used for a long time in the production of low‐cost point‐of‐care (POC) detection devices, most of which rely on the detection of colored bands by the user. However, test strips rarely provide the quantitative detection of biomarkers in clinical samples. In contrast, electrochemical detection enables quantitative detection in paper‐based immunoassays. Here, we demonstrate the production of a simple and economical lateral‐flow electrode device using only screen printing. Contrary to previous work, this device is used to simplify the washing and detection of a short and sensitive immunomagnetic assay for myeloperoxidase (MPO) detection. As we show, after incubation of the sample with magnetic beads (MBs) and detection antibody (Ab) for only 5 min, the whole reaction mixture can be directly pipetted onto the strip. Washing and detection can then be performed, as the MBs are retained with the aid of a magnet, and minimal user intervention is needed. The obtained results reveal that MPO can be detected in 1 : 100 diluted serum with limits of detection and quantification of 0.18 and 0.62 ng mL−1, respectively, in less than 15 min. Quantitative test strips: Printing electrodes directly on lateral‐flow membranes facilitates the quantification of conventional enzyme‐labelled immunoassays. A complete magneto‐immunoassay can be carried out on a test strip with amperometric detection, achieving detection limits in the ng mL−1 range within a few minutes.