Technologies: Solid-phase

Solid-phase: how it works

Step 1: Incubate in specimen

The dipstick is placed in the specimen and incubated to allow analyte (if present) to bind to the analyte capture molecule. Non-specific binding can occur with molecules other than analyte.

Step 2: First wash

Non-specific binding molecules are washed away by incubating the dipstick in wash buffer.

Step 3: Incubation with detection agent

The dipstick is then incubated in a solution containing the detection molecule. The detection molecule consists of two components: one that binds the analyte specifically and another that facilitates visual detection. In most modern tests, visualization isdue to the use of microscopic particles (such as latex beads or colloidal gold) which are visible when they aggregate. Some tests however uitilize traditional enzyme immunoassay chemistry to produce a precipitate that is visual t the naked eye.

Some of the analyte detection molecule might stick non-specifically to the solid substrate.

Step 4: Second wash

Non-specific binding of detector molecule is washed away aby a second incubation in wash buffer.

Step 5: read result

The dipstick is removed from the wash solution and read. If analyte is present in the specimen, a spot will be visible.