Development of lateral flow immunoassay system based on superparamagnetic nanobeads as labels for rapid quantitative detection of cardiac troponin I

In this study, superparamagnetic nanobeads (SPMNBs) were used as labels to establish a lateral flow immunoassay system for rapid, quantitative detection of cardiac troponin I (cTnI). First, the immunobeads were prepared by coupling monoclone antibody specific to cTnI onto SPMNBs. Then some factors which may influence the detection sensitivity of this lateral flow immunoassay system were studied, such as the amount of antibody immobilized in the Test line, sample volume and the amount of antibody per SPMNB. Finally, lateral flow test strips for detection of cTnI were established and applied to testing standard samples of different cTnI concentrations, which were also measured by Enzyme-linked Immunosorbent Assay (ELISA) in parallel. Furthermore, testing time and stability of magnetic signal were also investigated in this study. Results showed that this lateral flow test for cTnI had a high detection sensitivity of 0.01 ng/ml with a wide detection range of 5 orders of magnitude. The testing time was less than 15 min, and no significant decline of magnetic signal was observed in 140 days. Therefore, this lateral flow immunoassay system using SPMNB as labels will be a new point of care test (POCT) for rapid, quantitative detection of cardiac troponin I.