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

BACKGROUND: 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). METHODS: 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. RESULTS: 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 mu g/L. The linear measurement ranges for hs-cTnI and Myo were 1-10 000 ng/L and 1-10 000 mu g/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 < 11% for both hs-TnI and myo. CONCLUSIONS: The described proof-of-principle LFIA method could be used as a point-of-care device in multiple protein quantification and semiquantitative analysis. (C) 2011 American Association for Clinical Chemistry