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How can gold nanoparticles reveal the presence of a matching DNA sequence?

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The powers of 10 — nanotechnology Examples from biological and mechanical realms illustrate various “orders of magnitude” (powers of 10), from 10⁻² meter down to 10⁻⁷ meter.

To detect a specific DNA sequence using gold nanoparticles, researchers utilize a process based on molecular binding and optical change.1

The method involves splitting a single-stranded complementary DNA segment—which corresponds to the target genetic sequence—into two halves. One half is attached to a first set of gold particles, while the second half is attached to a separate set of gold particles.1

When the target DNA sequence is present in a solution, these two sets of gold particles bind to the matching sequence, causing the particles to agglomerate (clump together). This agglomeration results in a significant change in the optical properties of the solution, which is visible as a distinct change in color. If the target sequence does not match, no binding occurs, the particles remain dispersed, and no color change is observed.1