Branched DNA assay

In biology, a branched DNA assay is a signal amplification assay (as opposed to a target amplification assay) that is used to detect nucleic acid molecules.

From the base up, a branched DNA assay begins with a dish or some other solid support (e.g., a plastic dipstick). The dish is peppered with small, single stranded DNA molecules (or chains) that 'stick up' into the air. These are known as capture probe DNA molecules. Next, an extender DNA molecule is added. Each extender has two domains, one that hybridizes to the capture DNA molecule and one that "hangs out" in the air. The purpose of the extender is two-fold. First, it creates more available surface area for target DNA molecules to bind, and second, it allows the assay to be easily adapted to detect a variety of target DNA molecules.