Chemiluminometric Immunosensor for High-Sensitivity Cardiac Troponin I Employing a Polymerized Enzyme Conjugate as a
Guei-Sam Lim1,2, Sung-Min Seo1, Sung-Ho Paek1
1Department of Bio-Microsystem Technology, Korea University, Sungbuk-gu, Seoul 136-701, Korea.
Insights
A new rapid immunosensor detects high-sensitivity cardiac troponin I (hs-cTnI) with improved sensitivity. This cost-effective point-of-care test offers accurate results within 25 minutes.
Area of Science:
- Biomedical Engineering
- Analytical Chemistry
- Immunosensing
Background:
- High-sensitivity cardiac troponin I (hs-cTnI) is crucial for diagnosing myocardial infarction.
- Current point-of-care detection methods for hs-cTnI lack sufficient sensitivity and speed.
- Enhanced sensitivity is achievable using larger molecular tracers and sequential binding strategies.
Purpose of the Study:
- To develop a rapid and highly sensitive immunosensor for point-of-care detection of hs-cTnI.
- To utilize a novel tracer system and 2D chromatographic technology for enhanced detection.
- To achieve cost-effective hs-cTnI measurement compared to existing automated systems.
Main Methods:
- Development of a rapid immunosensor using streptavidin-conjugated polymerized horseradish peroxidase (SA-Poly-HRP) as a tracer.
- Implementation of a 2-dimensional chromatographic technology for sequential antigen-antibody complex formation and tracer binding.
- Chemiluminometric signal detection using a cooled charge-coupled device after HRP substrate addition.
Main Results:
- The developed immunosensor achieved a detection limit of 0.003 ± 0.001 ng/mL for hs-cTnI, a 10-fold improvement over plain enzyme tracers.
- Analysis time was completed within 25 minutes.
- Results showed excellent correlation (R² > 0.99) with the CentaurXP® reference system.
Conclusions:
- The rapid immunosensor enables highly sensitive and cost-effective detection of hs-cTnI at the point of care.
- The 2D chromatographic approach with SA-Poly-HRP tracer significantly enhances detection sensitivity.
- This technology offers a promising alternative to current automated hs-cTnI diagnostic platforms.
Abstract:
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.
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