Immunochromatography Assay (ICA), also known as lateral flow immunoassay, is a rapid diagnostic test used to detect the presence or absence of a target analyte in a sample. It operates on the principle of antigen-antibody interactions and involves the migration of a liquid sample through a porous membrane via capillary action.
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Immunochromatography Assay (ICA)
Immunochromatography Assay (ICA), also known as lateral flow immunoassay, is a rapid diagnostic test used to detect the presence or absence of a target substance (analyte) in a sample. It relies on the principles of antigen-antibody interactions to generate a visible signal, typically in the form of colored lines, within minutes. ICA is widely used in medical diagnostics, veterinary medicine, food safety, environmental monitoring, and research. It is known for its simplicity, speed, and ability to provide qualitative or semi-quantitative results without the need for sophisticated laboratory equipment.
Principle
The lateral flow immunoassay, or immunochromatography assay (ICA), is a quick diagnostic test that uses the concepts of antigen-antibody interactions to find out whether a target analyte is present in a sample or not. Usually, a liquid sample is migrated across a porous membrane by capillary action, where target antigens and mounted antibodies interact specifically.
Components
- Sample Pad: The area where the sample is applied, such as blood, urine, or saliva.
- Conjugate Pad: Consists of antigens or conjugated antibodies labeled with a measurable marker (such as fluorescent dyes or colloidal gold).
- Membrane: Immobilized capture antibodies combined with nitrocellulose or a comparable substance.
- Absorbent Pad: Captures surplus liquid and promotes circulation.
Steps
- Application of the Sample: The sample is put onto the sample pad.
- Migration: The conjugate pad is rehydrated by the sample being carried along the strip by capillary action.
- Antigen-Antibody Binding: In the conjugate pad, the labeled antibodies bind to the target antigen if it is present in the sample.
- Capture: The antigen-antibody complex moves toward the membrane and attaches itself to capture antibodies that have been rendered immobile.
- Visualization: If the target antigen is present, a visible signal (such as a colored line) will appear at the test line. A control line, which is made up of immobilized antibodies against the conjugate, guarantees that the test is operating as intended.
Merits
- Quick Results: Usually yields outcomes in a matter of minutes.
- Simple to Use: Needs little in the way of equipment or training.
- Portability: Fit for point-of-care examination in a range of environments.
- Detects a broad variety of analytes (antigens, antibodies, proteins) with versatility..
Limitations
- Sensitivity: In comparison to assays conducted in laboratories, it might be less sensitive.
- Specificity: There may be cross-reactivity with similar antigens.
- Results from quantitative analysis are often qualitative or semi-quantitative.
- Depending on the user Interpretation: Since results might vary widely, interpretation is necessary.
Applications
- Medical Diagnostics: Rapid testing for infectious diseases (e.g., HIV, malaria), pregnancy, cardiac markers, and drug abuse.
- Food Safety: Detection of allergens, toxins, and pathogens in food products.
- Environmental Monitoring: Detection of contaminants in water and soil.
Frequently Asked Question
What is Immunochromatography Assay (ICA) ?
Immunochromatography Assay (ICA), also known as lateral flow immunoassay, is a rapid diagnostic test used to detect the presence or absence of a target substance (analyte) in a sample. I
What is the purpose of immunochromatography test?
The purpose of an immunochromatography test is to rapidly detect the presence or absence of a specific analyte, such as an antigen or antibody, in a sample. This is commonly used for medical diagnostics, food safety, environmental monitoring, and various other applications where quick and reliable results are needed.
Can immunochromatography detect pregnancy in urine?
Yes, immunochromatography can detect pregnancy in urine by identifying the presence of human chorionic gonadotropin (hCG), a hormone produced during pregnancy.
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