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.
1 Method 2 Uses and Advantages 3 See also 4 Notes and references 5 External links
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
Once the capture and extender molecules are in place and they have
hybridized, the sample can be added. Target molecules in the sample
will bind to the extender molecule. This results in a base peppered
with capture probes, which are hybridized to extender probes, which in
turn are hybridized to target molecules.
At this point, signal amplification takes place. A label extender DNA
molecule is added that has two domains (similar to the first
extender). The label extender hybridizes to the target and to a
pre-amplified molecule. The preamplifier molecule has two domains.
First, it binds to the label extender and second, it binds to the
amplifier molecule. An example amplifier molecule is an
oligonucleotide chain bound to the enzyme alkaline phosphatase.
Diagrammatically, the process can be resembled as
Base → Capture Probe → Extender → Target → label extender →
pre-amplifier → amplifier
Uses and Advantages
The assay can be used to detect and quantify many types of
Notes and references
^ Ariffin, Siti Noor Fathilah Ahmad (2013). "Branched DNA: A Novel Technique for Molecular Diagnostics in Bone Studies" (PDF). Research Updates in Medical Sciences (RUMeS). 1 (1): 27–29. ^ a b Collins, M. L.; Irvine, B.; Tyner, D.; Fine, E.; Zayati, C.; Chang, C.; Horn, T.; Ahle, D.; Detmer, J.; Shen, L. P.; Kolberg, J.; Bushnell, S.; Urdea, M. S.; Ho, D. D. (1997). "A branched DNA signal amplification assay for quantification of nucleic acid targets below 100 molecules/ml". Nucleic Acids Research. 25 (15): 2979–2984. doi:10.1093/nar/25.15.2979. PMC 146852 . PMID 9224596.
Branched DNA Assay at the US National Library of Medicine Medical Subje