Colloidal Gold
Definition
Nanometre-scale gold particles that appear red or pink in visible light. Widely used as the reporter particle in lateral-flow strips because they are stable, easy to conjugate to antibodies, and produce a strong colour signal without enzymatic amplification.
- Scale
- Nanometre-sized gold particles
- Appearance
- Red or pink in visible light
- Role
- Reporter particle in lateral-flow strips
- Advantage
- Strong colour signal without enzyme amplification
Common questions
Why is colloidal gold preferred over an enzyme-based label?+
An enzyme label needs a separate substrate addition step and incubation time to develop colour, while colloidal gold is visible directly once bound, which keeps the lateral-flow strip a fast, single-step test with no additional reagents.
What determines the colour intensity seen on a test line?+
Particle size and concentration control the intensity: larger or more densely packed gold particles produce a darker line, which is why manufacturers tune particle synthesis carefully to get a reliably visible result at the lowest detectable analyte concentration.
Related terms
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- RSID (Rapid Stain Identification)
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- Sandwich Immunoassay
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