To successfully draw a valid conclusion in research and diagnostics, researchers require highly accurate detection and quantification of biomolecules in samples. The biomolecule can be a protein, hormone, antibody, or pathogen.
Higher sensitivity, improved accuracy, and faster analysis are desired in immunoassays. An immunoassay is a biochemical test that measures the presence or concentration of a biomolecule.
Traditionally, researchers have relied on enzyme-based and radioimmunoassays for testing. While these techniques are effective, they lack the sensitivity required to detect extremely low concentrations of analytes. Moreover, some of these older methods involve complex procedures, and some use hazardous reagents.
Chemiluminescent immunoassay is one of the advanced techniques that overcome these limitations of traditional immunoassays.
What is a Chemiluminescent Immunoassay?
Chemiluminescent immunoassay is a technique that detects and measures biomolecules in biological samples such as blood, serum, plasma, or cell culture fluids. The technique is based on the principle that antibodies bind selectively to their corresponding antigens.
It is a highly specific interaction that allows scientists to identify particular molecules even in complex mixtures. The interaction between antigen (the molecule) and antibody leads to a chemical reaction that emits light as a byproduct.
Researchers use specialized instruments to measure the intensity of the light, which allows them to analyze the concentration of the analyte present in the sample. Researchers can identify target molecules even at very low concentrations.
The CLIA method using the chemiluminescent immunoassay CLIA Kit produces rapid, reliable results in clinical diagnostics, pharmaceutical research, and immunology.
Principle of Chemiluminescent Immunoassay
Introducing the Sample and Targeting
The process begins by adding a biological sample to the assay system. The sample can be plasma or a cell culture fluid.
During this stage:
- The sample is introduced into a reaction chamber or microplate well.
- A capture molecule is immobilized on a solid surface.
- If present, the target analyte binds specifically to the immobilized capture molecule.
This interaction allows the assay to isolate the target molecule in the sample.
Removing Unbound Substances
The binding is followed by washing, which helps remove materials that do not play a role in the reaction.
This step:
- Eliminates non-specific substances from the sample
- Reduces background signal
- Improves overall assay accuracy
Washing ensures that the molecules of interest remain attached to the solid surface.
Introducing the Chemiluminescent Label
A detection molecule carrying a chemiluminescent label is added to the reaction system.
The label contains a special compound that emits light after undergoing a chemical reaction. It produces a high-intensity signal.
Chemical Reaction
A specific substrate or triggering reagent is added after the formation of the detection complex. This is when:
- The labeled compound undergoes a chemical transformation.
- Energy released during the reaction is emitted as light.
The emitted light is proportional to the amount of analyte present. The reaction produces a strong, measurable signal because light is emitted rapidly and efficiently.
Detecting and Quantifying the Signal
Specialized instruments, such as luminometers or photomultiplier detectors, are used to detect the light emitted during the reaction. The detection system:
- Captures the emitted photons
- Converts the light signal into an electrical signal
- Records the signal intensity for analysis
The measured signal is compared with a calibration curve generated from standards of known concentration to determine the analyte concentration.
Data Interpretation
Analytical software processes the data and calculates the concentration of the target molecule in the sample.
Advantages of Chemiluminescent Immunoassay
When compared with many conventional immunoassay methods, chemiluminescent immunoassay offers the following advantages:
High Analytical Sensitivity
This method can detect extremely small amounts of biomolecules in biological samples, as light-emission signals can be measured with very high precision using optical instruments.
Wide Dynamic Range
Researchers can use chemiluminescent immunoassays to measure both low and relatively high concentrations of analytes within the same assay system. No extensive sample dilution is required.
Rapid Detection and High Throughput
The reaction is rapid, allowing faster analysis. Modern instruments can process a large number of samples in a short period of time.
Improved Specificity
The strong, selective interaction between antibodies and their target molecules results in high accuracy. Improved specificity:
- Reduces interference
- Minimizes false positives or false negatives
- Improves overall reliability
Enhanced Reproducibility
Reproducibility is essential for immunoassays to ensure consistent, reliable results.
Standardized reagents, controlled reaction conditions, and automated instrumentation contribute to consistent and reliable results.
