Labeled Immunoassay Flashcards
Designed for antigens and antibodies that may be small in size or present in very low concentrations
Labeled Immunoassays
is labeled by attaching a particle or molecule that will better detect lower concentration of antigen-antibody binding
Binding agent
Examples of analytes determined using labeled immunoassays?
- Bacterial antigens
- Hormones
- Drugs
- Tumor markers
- Specific immunoglobulins
- Other proteins
Types of Labels?
- Radionuclides
- Enzymes
- Fluorochromes
- Luminescent
atoms with unstable nuclei that spontaneously emit radiation?
Radionuclides
Emits beta particles or positron?
Beta radiation
beta particles are?
Negatively charged
positrons are?
Positively charged
most common radionuclide for diagnosis and research in cellular immunology?
Tritium (3H)
is tritium beta or gamma?
Beta
Electromagnetic radiation with very short wavelength from an unstable nuclei
Gamma radiation
most common in the clinical lab due to its longer half-life and appropriate energy level?
125I
releases energy from decay of nuclei as it becomes more stable
Gamma radiation
Detected using a crystal scintillation counter
Gamma radiation
crystal scintillation counter aka?
Gamma counter
Originally used to determine insulin-anti-insulin complexes in diabetic patients and is useful in measuring analytes occurring at trace concentrations
Radioimmunoassay
who developed RIA?
Yalow and Berson
disadvantages of RIA
health hazard and disposal problems
react with suitable substrates to produce breakdown products that are either chromogenic, fluorogenic, or luminescent and developed as alternatives to RIAs
Enzyme Immunoassay
Commonly used enzyme labels
- Horseradish peroxidase
- Alkaline phosphatase
- B-D-galactosidase
Uses fluorochromes or fluorophores
Fluorescent labels
Common fluorescent compounds used
Fluorescein and Rhodamine
use labels that emit light as the result of electrical or chemical (oxidation) reaction?
Chemiluminescence
Types of luminescent labels?
- Luminol
- Acridinium esters
- Ruthenium derivatives
- Nitrophenyl oxalates
uses electrochemical compounds that generate light when redox reaction occurs?
Electrochemiluminescence immunoassay
Labeled antigen competes with unlabeled antigen for a limited number of antibody-binding sites
Competitive Immunoassay
Competitive Immunoassay (inversely or directly proportional) to unlabeled antigen concentration
inversely proportional
Unknown antigen is bound by passive adsorption to the solid phase and Label activity is directly proportional with antigen concentration
Direct Noncompetitive Immunoassay
Initial antigen adsorption and washing and Label activity is directly proportional with antigen concentration
Indirect Noncompetitive Immunoassay
Uses known unlabeled antibody to bind the immobilized unknown antigen
Indirect Noncompetitive Immunoassay
Incubated with the labeled antibody
Direct Noncompetitive Immunoassay
Similar with direct immunoassay but antibody, rather than antigen is passively adsorbed on the solid phase
Capture/Sandwich Immunoassay
Requires compatible known antibody pair (unlabeled and labeled) that binds different epitopes on the unknown antigen
Capture/Sandwich Immunoassay
uses conjugated antibody that binds with the immobilized antigen-antibody complex on the plate well
Direct Capture/Sandwich Immunoassay
uses either an unconjugated antibody or biotinylated antibody that binds to the immobilized antigen-antibody complex and subsequently detected by a secondary labeled antibody
Indirect Capture/Sandwich Immunoassay
Originally designed for POCT or home-based testing
Rapid Immunoassays
Designed as a single use, disposable assays in a plastic cartridge
Rapid Immunoassays
Membrane based and easy to perform
Rapid Immunoassays
Interpreted by looking at the formation of a colored reaction product
Rapid Immunoassays
membrane material; easily immobilizes proteins
Nylon
Combines all steps of rapid immunoassay in one
Immunochromatography
