14mer

A 14mer is an oligonucleotide consisting of fourteen nucleotides. In nucleic acid chemistry and molecular biology, the term “mer” denotes the number of monomer units in a polymer, so a 14mer can be a DNA or an RNA sequence. These short oligos are commonly used as primers, probes, or barcode elements in various assays and detection platforms.

Synthesis and purification of 14mers are carried out by solid-phase synthesis, typically using phosphoramidite chemistry on a controlled-pore glass support. After assembly, the molecule is cleaved from the support and deprotected, and the product is purified by methods such as high-performance liquid chromatography (HPLC) or polyacrylamide gel electrophoresis to remove truncated sequences. Both DNA and RNA versions exist, and 14mers may be modified at the 5' or 3' ends with fluorescent labels, quenchers, or other functional groups to suit specific applications.

Biophysical properties of 14mers depend strongly on sequence and salt conditions. The melting temperature (Tm) of a 14-nucleotide duplex is highly sequence-dependent; GC-rich sequences tend to have higher Tm than AT-rich ones. In general, shorter oligos have lower stability and require careful design to achieve the desired binding characteristics. Because of their short length, 14mers can be prone to non-specific binding or off-target interactions, so they are often used as probes or anchors rather than primers for amplification in standard PCR.

Applications and limitations: 14mers are useful in microarrays, detection assays, and barcode-based experiments where short, specific binding is sufficient. They are less commonly used as PCR primers due to limited specificity and stability. Modifications and careful sequence design can mitigate some limitations for targeted detection or diagnostic assays.

See also: Oligonucleotide, Primer, DNA oligonucleotide, Nucleic acid hybridization.