Chemiluminometric Immunosensor for High-Sensitivity Cardiac Troponin I Employing a Polymerized Enzyme Conjugate as a Tracer

• Published in: Scientific reports Vol. 5; no. 1; p. 14848
• Main Authors: Lim, Guei-Sam, Seo, Sung-Min, Paek, Sung-Ho, Kim, Seung-Wan, Jeon, Jin-Woo, Kim, Dong-Hyung, Cho, Il-Hoon, Paek, Se-Hwan
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 07.10.2015
• Subjects: Biosensing Techniques - methods; Biotin; Biotin - metabolism; Calcium-binding protein; Enzyme-Linked Immunosorbent Assay; Enzymes; Heart; Heart diseases; Horseradish peroxidase; Horseradish Peroxidase - metabolism; Humans; Immunoassay - methods; Limit of Detection; Luminescent Measurements - methods; Peroxidase; Streptavidin; Streptavidin - metabolism; Troponin; Troponin I; Troponin I - analysis; Troponin I - metabolism
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep14848

To detect high-sensitivity cardiac troponin I (hs-cTnI; <0.01 ng/mL) at points of care, we developed a rapid immunosensor by using horseradish peroxidase polymerized in 20 molecules on average (Poly-HRP) as a tracer conjugated with streptavidin (SA-Poly-HRP). As shown in the conventional system, enhanced sensitivity could be achieved by using a sequential binding scheme for the complex formation to contain the huge molecular tracer. We used a 2-dimensional chromatographic technology to carry out the sequential bindings in cross-flow directions. After the complex formation of antigen-antibody with analyte in a vertical direction, SA-Poly-HRP was horizontally supplied across the membrane strip for additional binding via a biotin-SA linkage. The HRP substrate was subsequently supplied along the same direction to produce a chemiluminometric signal, which was measured by a cooled charge-coupled device. Hs-cTnI analysis was completed in this format within 25 min, and the results showed a high correlation with those of the CentaurXP® reference system (R(2) > 0.99). The detection limit of the rapid immunosensor was 0.003 ± 0.001 ng/mL cTnI, corresponding to a 10-fold improvement compared to results using the plain enzyme tracer. This demonstrated the measurement of hs-cTnI in a much more cost-effective manner compared to the automated versions currently available.