Enzyme-Linked Immunosorbent Assay (ELISA)
Enzyme-linked immunosorbent assay (ELISA) is a fundamental biochemical technique that plays a crucial role in modern diagnostics and biomedical research.
The ELISA technique enables the detection and quantification of specific proteins, antibodies, hormones, and antigens in biological samples. Whether you’re in a clinical laboratory, a research facility, or an industrial setting, ELISA will prove to be useful for multiple types of applications.
How it works
- Coating
In a microplate well, a target antigen is immobilized on a solid surface, such as the well’s bottom. This is achieved by coating the well with a capture antibody specific to the antigen of interest. To prevent non-specific binding, any remaining exposed surfaces in the well are blocked with an inactive substance. - Sample Addition
The biological sample containing the antigen is added into the well, allowing any antigen present to attach to the immobilized capture antibody. Calibrators and controls are also added at this point. - Washing
The well is later thoroughly washed to remove any unbound substances. This step can be done several times throughout the ELISA procedure. - Primary Antibody
An antibody, tagged with an enzyme, is added. The antibody is designed to bind to the target antigen. If the antigen is present, it binds to the antigen-antibody complex, creating a “sandwich” structure. - Enzyme Substrate
A substrate specific to the enzyme attached to the primary antibody is added. When the substrate interacts with the enzyme, it produces a detectable signal, a color change, or chemiluminescent light. - Measurement
The signal generated is quantified using a spectrophotometer or luminometer, and the intensity of the signal is directly proportional to the amount of antigen present in the sample.
ELISA Applications
ELISA’s adaptability extends to a multitude of applications, making it an invaluable tool in laboratories worldwide. Here are a few examples:
Clinical Diagnostics
The ELISA technology is very important in clinical diagnostics due to its high sensitivity and specificity qualities. ELISAs are commonly utilized for the detection of various diseases, including but not limited to:
- Infectious Diseases
ELISA is widely used when diagnosing diseases like HIV, hepatitis, and COVID-19. It detects specific antibodies or antigens present in patient samples, aiding in early disease detection and monitoring treatment effectiveness. - Autoimmune Diseases
ELISA is also crucial in the diagnosis of autoimmune conditions such as multiple sclerosis, rheumatoid arthritis, and type 1 diabetes since it can be used to identify autoantibodies and other biomarkers that can help clinicians confirm these diseases.
Drug Discovery
Within pharmaceutical research, ELISAs serve as a key instrument for drug discovery and development, providing invaluable assistance to researchers through:
- Biomarker Analysis
ELISA aids in the identification and quantification of specific biomarkers linked to diseases or potential drug targets. The information obtained through an ELISA can then serve as a valuable guide for formulating precisely targeted therapeutic strategies. - Drug Efficacy Testing
ELISA is used by researchers to evaluate how potential drug candidates influence these biomarkers, a critical stage in the process of identifying promising drugs for further advancement.
Environmental Monitoring
ELISA is used to detect and quantify contaminants, toxins, or pollutants in environmental samples.
Food Safety
The technique is applied in the food industry to detect allergens, pathogens, or residues, ensuring food safety.
