Immobilization analyte

Within ELIS As, both direct and indirect modes of performance are possible. The former are based on competition between the analyte and an enzyme-labeled analyte for a place on an immobilized antibody. The latter is based on competition between the analyte and an immobilized analyte for a place on an enzyme-labeled... 

Fig. 9.7. Indirect competitive immunoassay with immobilized analyte The anal5de competes with in immobilized analyte derivative for a limited amount of antibodybinding sites (1) until equilibrium (2) is established. The surplus of analyte and antibody (3) are removed by washing of the solid support and an excess of labelled secondary anti-immunoglobulin smtibody (4) is added onto the solid support. After the excess of secondary antibody is removed (5), the fraction of bound label is detected (6).

Pass this mixture through the flow cell containing the crystal modified with immobilized analyte (or its derivative that is recognized by the antibody). 

The piezoelectric crystal modified with immobilized analyte should be saturated with the corresponding antibody. 

Fig. 5 Cartoon representations of three different assays typically used in detecting analytes with an SPR biosensor, a Sandwich assay involves the capturing of analyte by a sensing element immobilized on the sensor surface. This is followed by the binding of a secondary antibody for amplification, b In a competitive assay, native analyte and analyte conjugated to a larger protein compete to bind to an immobilized sensing element on the surface, c In an inhibition assay, analyte is incubated with a fixed concentration of antibody. This incubation solution is then passed across a surface of immobilized analyte. Free antibody binds to the sensor siuface, creating an inverse relationship between concentration of analyte in the sample and sensor response...

Alternatively, microfluidic systems can be designed to take advantage of the evanescent field by immobilizing analyte-sensitive fluorescent dye on the surface of the on-chip waveguide. In this configuration, the evanescent energy field... 

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