Conjugate Pad
Definition
A zone upstream of the test and control lines containing dried detection antibodies pre-bound to colloidal gold or coloured latex particles. On sample contact, the conjugate rehydrates and migrates with the liquid front.
- Location
- Upstream of test and control lines
- Contents
- Dried detection antibodies bound to gold/latex particles
- Trigger
- Rehydrates on sample contact
- Device type
- Lateral-flow / immunochromatographic assay
Common questions
What happens if the conjugate pad fails to rehydrate properly?+
If the labelled antibodies do not release and migrate with the sample, neither the test nor control line will develop colour, producing an invalid result rather than a false negative. This is why a functioning control line is checked before a lateral-flow result is interpreted as valid.
How does the conjugate pad's particle choice affect result readability?+
Colloidal gold particles produce a red-to-purple line visible to the naked eye, while coloured latex particles can be tuned to other visible colours or, in some assay designs, to fluorescent or magnetic detection for more sensitive quantitative readers. The choice affects both visibility and the sensitivity achievable by the assay.
Related terms
- ABAcard HemaTrace
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- Colloidal Gold
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- Nitrocellulose Membrane
- The porous polymer strip along which sample fluid wicks by capillary action. The test and control line antibodies are immobilised directly on...
- RSID (Rapid Stain Identification)
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- Sandwich Immunoassay
- The detection architecture used by most lateral-flow strips for large antigens: the target antigen is captured between two antibodies, the conjugated detection...