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Development of a low density colorimetric protein array for cardiac troponin I detection
Huishi Guo1, Di Yang, Chunrong Gu
1Research Institute of Cardiovascular Disease, First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, P R. China.
Insights
A new, rapid immunoassay for cardiac troponin I (cTnI) offers a faster and cost-effective alternative to ELISA. This quantitative assay provides reliable results for cTnI detection in patient serum samples.
Area of Science:
- Biochemistry
- Immunology
- Medical Diagnostics
Background:
- Cardiac troponin I (cTnI) is a critical biomarker for diagnosing myocardial infarction.
- Existing diagnostic methods like ELISA are time-consuming and resource-intensive.
Purpose of the Study:
- To develop a rapid, inexpensive, and reliable quantitative immunoassay for cardiac troponin I (cTnI).
- To evaluate the performance of the new assay compared to conventional ELISA.
Main Methods:
- A one-step dual monoclonal antibody "sandwich" immunoassay utilizing a low-density protein array.
- Nanogold probes and silver enhancement for signal amplification.
- Detection of cTnI in small serum samples within 40 minutes.
Main Results:
- The assay demonstrated high specificity for cTnI with minimal cross-reactivity.
- A cut-off value of 0.3 ng/ml was established using a control group.
- Validation with 588 patient samples showed no significant difference (P=0.66) and 86% agreement with ELISA.
Conclusions:
- The developed colloidal gold-based immunoassay is a rapid, cost-effective, and reliable method for cTnI detection.
- This assay offers a significant improvement over traditional ELISA in terms of speed and simplicity.
- The method is suitable for clinical settings requiring quick and accurate cardiac troponin I measurements.
Abstract:
This work presented a rapid, inexpensive, reliable, and flexible quantitative immunoassay for cardiac troponin I (cTnI). The assay was based on the concepts of one-step dual monoclonal antibody "sandwich" principle, the low density protein array, the nanogold probe, and the silver enhancement on the gold particles. The capture antibody (IgG1) coated supporting nitrocellulose membrane and the colloidal gold-labeled detection antibody (cAu-IgG2) were prepared before the detection. The detection procedure involved two steps, i.e., immunoreaction and silver amplification. The assay needs only small amounts of serum samples of patients, The whole detection procedure of the assay could be fulfilled within 40 min (much faster than the routine enzyme-linked immunosorbent assay (ELISA) that takes usually at least 3 hours for a turnaround test). The detection results could be easily imaged with a simple flatbed scanner or even observed with the naked eye. The assay showed good specific response to cTnI with very little cross-reactivity to the skeletal isoforms of troponin I (sTnl), cardiac troponin T (cTnT), and myoglobin (Mb). A cut-off value of 0.3 ng/ml was obtained from a reference control group (200 normal serum samples). 588 patients' serum samples were assayed simultaneously by routine ELISA and this colloidal gold method to test the validity of the method. The data were analyzed using the statistical package SPSS version 11.0 (SPSS Inc.) There was no significant difference between these two assays (P = 0.66 > 0.05). The agreement between this method (> or < 0.3 ng/ml) and ELISA was 86%.
