Simultaneous Detection of High-Sensitivity Cardiac Troponin I and Myoglobin by Modified Sandwich Lateral Flow Immunoassay: Proof of Principle

Although numerous lateral flow immunoassays (LFIAs) have been developed and widely used, inadequate analytical sensitivity and the lack of multiple protein detection applications have limited their clinical utility. We developed a new LFIA device for the simultaneous detection of high-sensitivity cardiac troponin I (hs-cTnI) and myoglobin (Myo). We used a gold nanoparticle (AuNP) doubly labeled complex, in which biotinylated single-stranded DNA was used as a linkage to integrate 2 AuNPs and streptavidin-labeled AuNP, as an amplifier to magnify extremely low signals. The detection limit of 1 ng/L achieved for hs-cTnI was 1000 times lower than that obtained in a conventional LFIA. The detection limit for simultaneously measured Myo was 1 μg/L. The linear measurement ranges for hs-cTnI and Myo were 1-10 000 ng/L and 1-10 000 μg/L, respectively. We observed concordant results between the LFIA and clinical assays in sera from 12 patients with acute myocardial infarction (hs-cTnI r = 0.96; Myo r = 0.98). Assay imprecision was