Solid Phase
Definition
The inert surface to which an antigen or antibody is adsorbed at the start of an ELISA. Usually the well walls of a polystyrene microplate. Immobilisation allows unbound material to be removed by washing without losing the bound target.
- Role
- Inert surface to which antigen or antibody is adsorbed in ELISA
- Typical form
- Well walls of a polystyrene microplate
- Function
- Immobilises target so unbound material can be washed away
- Assay type
- Enzyme-linked immunosorbent assay (ELISA)
Common questions
What happens if the solid phase does not bind the antigen or antibody well?+
Poor adsorption reduces assay sensitivity and can cause inconsistent results across wells, since weakly bound capture molecules wash off during the rinse steps along with the material meant to be removed, so plate quality and coating conditions are controlled variables in validated protocols.
Is the solid phase specific to ELISA or used in other forensic immunoassays too?+
The same immobilisation principle underlies other solid-phase immunoassays and lateral-flow presumptive tests used in forensic biology, though ELISA on a microplate is the format where the term is most commonly applied.
Related terms
- Competitive ELISA
- An ELISA format in which sample antigen competes with a fixed quantity of labelled antigen for a limited number of antibody binding...
- Cross-Reactivity
- The capacity of an antibody raised against one analyte to bind structurally related compounds. In RIA, cross-reactivity is the main driver of...
- Enzyme Conjugate
- An antibody (or antigen) chemically linked to a reporter enzyme, most commonly horseradish peroxidase (HRP) or alkaline phosphatase (AP). The enzyme catalyses...
- Sandwich ELISA
- An ELISA format in which a capture antibody immobilised on the plate binds one epitope of the target antigen, and a separate...
- Substrate
- The compound converted by the reporter enzyme into a coloured product. For HRP, 3,3',5,5'-tetramethylbenzidine (TMB) is the standard substrate, producing a blue...