Immunoassays Quiz: ELISA and RIA Techniques

A method using tagged antibody-antigen complexes where radioactivity is detected using conventional techniques.

A technique that combines real-time quantitative polymerase chain reaction (RT-qPCR) with immunoassays, using DNA probes as labels.

Type of immunoassay employing fluorogenic reporters like phycoerythrin for detection.

Immunoassays that don't require labeling components, instead relying on detection methods like measuring changes in resistance or using surface plasmon resonance.

An example of a label-free immunoassay where binding between an antibody and an antigen is detected by measuring changes in surface plasmon resonance.

One type of immunoassay where the amount of unlabeled analyte in a sample is determined by its competition with a labeled analyte for binding to an antibody. The amount of bound labeled analyte is then measured.

A type of immunoassay where the amount of unlabeled analyte is determined by its competition with a labeled analyte for binding to an antibody. The labeled, unbound analyte is then separated, and the amount of remaining labeled, bound analyte is measured.

Widely used immunoassay technique that utilizes enzymes linked to antibodies to detect and quantify the target analyte. It involves a series of binding and washing steps to measure the amount of enzyme-linked antibody bound to the target.

A laboratory technique that uses antibodies to detect and quantify specific substances in biological samples. It utilizes enzyme-linked antibodies to produce a measurable signal.

The first step in ELISA involves attaching a capture antibody to a solid surface (e.g., a microplate well) that specifically binds to the target analyte.

After coating, the surface is blocked with a protein to prevent non-specific binding of other components in the sample. This ensures only the target analyte binds to the capture antibody.

The sample containing the target analyte is added to the well. If the target is present, it will bind to the capture antibody.

After incubation, the well is thoroughly washed to remove any unbound components, leaving only the target analyte bound to the capture antibody.

A detection antibody labeled with an enzyme (e.g., alkaline phosphatase or peroxidase) is added, which recognizes a different region of the target analyte, generating a signal.

A substrate that reacts with the enzyme on the detection antibody is added. This reaction produces a signal (color change or a light output) that is proportional to the amount of the target analyte.

The signal generated by the enzyme-substrate reaction is measured using a spectrophotometer or a similar device. The intensity of the signal directly corresponds to the concentration of the target analyte.

Enzyme-linked Immunosorbent Assay (ELISA) uses enzyme-linked antibodies to detect and quantify specific analytes in a sample. It involves a series of binding and washing steps to measure the amount of enzyme-linked antibody bound to the target.

ELISA is commonly used in clinical diagnostics to detect the presence of antigens or antibodies in biological samples.

ELISA is also employed for a wide range of applications, including disease diagnosis, autoimmune disorders, pregnancy tests, protein quantification, studying immune responses, and monitoring therapeutic drug levels.

Radioimmunoassay (RIA) is a type of immunoassay that uses a radioactive isotope to measure the concentration of target analytes in a biological sample.

RIA involves using a radiolabeled antigen or antibody to detect and quantify the presence of a specific target molecule in a sample.

RIA is based on the principle of competitive binding, where the labeled antigen competes with the unlabeled antigen in the sample for binding to a limited number of specific antibody sites.

The amount of radioactivity bound to the antibody is inversely proportional to the concentration of the target molecule in the sample.

RIA has many advantages, including high sensitivity, high specificity, and a wide range of applications.

A highly sensitive technique that utilizes light emission from a chemical reaction to detect and quantify specific analytes in biological samples.

The process where a specific antibody is attached to a solid surface like a microplate or bead. This capture antibody is designed to bind to the target analyte in the sample.

The step where the sample containing the target analyte is added to the capture antibody. If the analyte is present, it binds to the antibody, forming a complex.

A reagent containing an enzyme linked to an antibody is added. This enzyme triggers a chemical reaction that produces light when the antibody binds to the analyte.

A specialized detector, like a photomultiplier tube, measures the intensity of light emitted. This intensity directly correlates with the amount of target analyte present.

The ability of CLIA to detect even tiny amounts of analytes, making it suitable for applications like early disease diagnosis and detecting pathogens.

CLIA offers exceptional accuracy, providing reliable and precise measurement of target analytes.

CLIA uses a simple and streamlined protocol, making it relatively easy to perform and automate in laboratories.

CLIA uses a chemical reaction to generate light, enabling the detection and quantification of target analytes. This technique offers high sensitivity and can measure a wide range of analyte concentrations.

Selecting the appropriate immunoassay depends on the type of sample being analyzed, such as tissue homogenates or cell lysates, and requires consideration of the specific sample preparation techniques needed to achieve optimal assay performance.

CLIA is widely used in clinical labs to diagnose infections, monitor medication levels, and identify tumor markers.

The desired throughput and automation level influence the choice of immunoassay. Some assays are designed for high-throughput analysis (lots of samples quickly), ideal for clinical labs, while others are better for low-volume applications, where manual procedures are sufficient.

The type of molecule you want to detect (like a protein, DNA, or small molecule) determines the type of immunoassay you need.

Time and cost factors are crucial when selecting an immunoassay. Some provide quick results for rapid analysis and decision-making, while others need longer incubation periods. Cost includes reagents, consumables, and specialized equipment.

Running and interpreting immunoassays requires technical expertise. Ensure the availability of skilled personnel before choosing an assay, as not every laboratory has proficiency in every type.

The level of accuracy and precision needed influences the choice of immunoassay. High sensitivity is important for detecting small amounts, while high specificity minimizes false positives.

While expertise is essential, remember that people can be trained with proper qualifications. Consider the opportunity to build internal expertise if the chosen immunoassay requires specific skills not currently available.

The type of sample being analyzed (blood, urine, etc.) matters, as different immunoassays work best with specific samples.

The time it takes to run the assay is important, especially when speed is needed for diagnosis or treatment decisions.

The cost per test varies depending on the immunoassay. Budget constraints may influence the choice of assay.

The availability of equipment and trained personnel can influence the choice of immunoassay.