Integrated electrochemical lateral flow immunoassay: Scalable fabrication and wireless detection of cardiac troponin I

In recent years, electrochemical lateral flow immunoassay (eLFIA) has gained increasing attention in point-of-care testing (POCT) due to the combination of user-friendly lateral flow immunoassay (LFIA) with electrochemical detection featuring easy integration, high sensitivity, and rapid response. However, a key issue of eLEIA is how to build good connection between strip and electrodes. Current procedure often includes preparation of each part separately and manual adhesion afterwards. Such operation not only leads to poor reproducibility and unsatisfied sensing performance, but also faces difficulty in large-scale manufacture. Herein, we developed a novel eLFIA platform of which sensing electrodes were prepared directly on nitrocellulose membrane using screen printing technique. Further, a one-step detection method was established via sandwich immunoassay strategy, and the entire assay can be completed within 10 min. Using Cardiac Troponin I (cTnI) as the model analyte, we studied the sensing performance systematically. The sensor demonstrated good linearity in the concentration range of 0∼100 ng/mL with a detection limit of 0.29 ng/mL (S/N = 3). Moreover, a portable wireless signal acquisition POCT device was fabricated by integrating eLFIA with a portable potentiostat and a smartphone. The proposed eLFIA device contributes to the development of more efficient and appropriate diagnostic tools, particularly for POCT in clinical settings and domestics.