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Magnetic bead-sensing-platform-based chemiluminescence resonance energy transfer and its immunoassay application
Guoxin Qin1, Shulin Zhao, Yong Huang
1Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources (Ministry of Education), College of Chemistry and Chemical Engineering, Guangxi Normal University, Guilin, China.
Insights
A new competitive immunoassay uses chemiluminescence resonance energy transfer (CRET) on magnetic beads (MBs) to detect human immunoglobulin G (IgG). This method offers a sensitive and reliable way to quantify IgG in biological samples.
Area of Science:
- Analytical Chemistry
- Biochemistry
- Immunology
Background:
- Immunoassays are crucial for detecting biomarkers like human immunoglobulin G (IgG).
- Chemiluminescence resonance energy transfer (CRET) offers a sensitive detection mechanism.
- Magnetic beads (MBs) provide efficient separation and immobilization in assays.
Purpose of the Study:
- To develop a novel competitive immunoassay for human IgG detection.
- To utilize CRET on magnetic beads for enhanced sensitivity and specificity.
- To establish a reliable method for quantifying IgG in human serum.
Main Methods:
- Conjugation of magnetic beads with HRP-labeled anti-IgG antibodies.
- Immobilization of FITC-labeled IgG-antibody complexes on magnetic beads.
- Competitive immunoreaction with target human IgG analyte.
- Detection via CRET upon addition of chemiluminescence buffer.
- Magnetic separation to remove unbound substances.
Main Results:
- A linear relationship was observed between the CL intensity ratio and human IgG concentration (0.2-4.0 nM).
- High correlation coefficient (0.9965) and a low detection limit (2.9 × 10(-11) M) were achieved.
- The method was successfully applied to detect IgG in human serum samples.
Conclusions:
- The developed CRET-based immunoassay on magnetic beads is a promising tool for human IgG detection.
- This approach offers high sensitivity and specificity for quantifying IgG.
- The method has potential for detecting other antigen-antibody complexes.
Abstract:
A competitive immunoassay based on chemiluminescence resonance energy transfer (CRET) on the magnetic beads (MBs) is developed for the detection of human immunoglobulin G (IgG). In this protocol, carboxyl-modified MBs were conjugated with horseradish peroxidase (HRP)-labeled goat antihuman IgG (HRP-anti-IgG) and incubated with a limited amount of fluorescein isothiocyanate (FITC)-labeled human IgG to immobilize the antibody-antigen immune complex on the surface of the MBs, which was further incubated with the target analyte (human IgG) for competitive immunoreaction and separated magnetically to remove the supernatant. The chemiluminescence (CL) buffer (containing luminol and H(2)O(2)) was then added, and the CRET from donor luminol to acceptor FITC in the immunocomplex on the surface of MBs occured immediately. The present protocol was evaluated for the competitive immunoassay of human IgG, and a linear relationship between CL intensity ratio (R = I(425)/I(525)) and human IgG concentration in the range of 0.2-4.0 nM was obtained with a correlation coefficient of 0.9965. The regression equation was expressed as R = 1.9871C + 2.4616, and a detection limit of 2.9 × 10(-11) M was obtained. The present method was successfully applied for the detection of IgG in human serum. The results indicate that the present protocol is quite promising for the application of CRET in immunoassays. It could also be developed for detection of other antigen-antibody immune complexes by using the corresponding antigens and respective antibodies.
