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Describe how antibodies can be used to analyse biological samples
Because of the ease with which antibodies against biological materials can be prepared in
the lab + because of their great specificity antibodies form the core of many important
analytical + preparative biochemical procedures
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Immunocytochemistry
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This technique uses antibodies to help localise particular antigens in cytological
preparations
In the simplest form an antibody is conjugated with a fluorescent dye such as
fluorescein
A thin section of cell/tissue is then immersed in a solution of the fluorescent
antibody
After the excess is washed off → the bound antibody can be visualised by
fluorescence microscopy
It’s possible to visualise diff antigens within a cell simultaneously
using multiple dye-linked antibodies

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ELISA (Enzyme-Linked Immunosorbent Assay)
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96 well plates coated with a solution containing the sample mixture
Proteins stick non-specifically to the polystyrene surfaces of the well via Van der
Waal’s forces
Next a locking protein added to bind to any bare polystyrene surfaces → to prevent
non-specific binding of the antibody to the well
Primary antibody that specifically binds to the target antigen’s then added
This is the ‘immunosorbent’ part of the assay → in which the detection of a specific
antibody-antigen interaction occurs
Detection of this antigen-antibody interaction’s achieved using a secondary antibody
Secondary antibody crosslinked to an enzyme → horseradish peroxidase!
The development of colour in the wells of the plate indicates the
presence of the target antigen
Most widely used diagnostic test for HIV infections

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