Immunochemical Techniques Flashcards
Competitive formats use ________ reagents (antibody or other antigen binder)
LIMITED
Noncompetitive formats use _______ reagents (antibody or other antigen binder) and are two-site or “________” assays
EXCESS
sandwich
What does it mean that competitive immunoassays are simultaneous?
all reactants are mixed together simultaneously or at the same time
Simultaneous Competitive Immunoassay:
- Principle
Labled and unlabeled antigen compete for a limited number of binding sites on an antibody binder. Avidity for the antibody is the same for both.
Simultaneous Competitive Immunoassay:
- Proportionality observed between bound able and unlabeled antigen concentrations
The probability of labeled Ag binding to the antibody binder is inversely proportional to (unlabeled Ag)
Simultaneous Competitive Immunoassays
- Examples of tests
RIA, FIA, EIA
Noncompetitive Immunoassay:
- Principle
A captured antibody is bound to a solid phase. Unlabeled antigen reacts with the solid phase antibody, then there’s a washing step. Labeled antibody is added; it reacts with the unbound antigen on a 2nd and distinct epitope. Another washing step occurs, and the amount of the bound label is determined
Noncompetitive Immunoassay:
- Proportionality observed between bound able and unlabeled antigen concentrations
directly proportional
What is the difference of a heterogeneous immunoassays from homogeneous immunoassays?
Heterogeneous require a separation step to separate the bound label from the free, unbound reactants. Homogeneous do not require a separation step
EMIT:
- what does it stand for
Enzyme-Multiplied Immunoassay Technique
EMIT:
- What is detected
change in absorbance after adding substrate
EMIT:
- Homogeneous or heterogeneous
Homogenous
EMIT:
- Proportionality
direct
ELISA:
- what does it stand for
Enzyme-Linked Immunosorbent Assay
ELISA:
- what is detected
Change in absorbance
