12mers

A 12mer refers to a polymer or oligomer that contains twelve monomer units. The term is used across chemistry, molecular biology, and materials science to describe a discrete chain length, whether the monomers are nucleotides, amino acids, or other repeat units.

In nucleic acid work, a 12-mer is a DNA or RNA oligonucleotide of length 12. Such sequences serve as hybridization probes, primers, or standards in assays, and their properties depend on sequence composition. Melting temperature generally rises with higher GC content and with salt concentration; 12-mers typically have modest Tm values and can exhibit non-specific binding if design is poor. Design considerations include avoiding strong self-complementarity and secondary structure that could impair binding.

Synthesis and handling: 12-mers are usually produced by solid-phase synthesis using phosphoramidite chemistry for DNA or RNA, with stepwise coupling efficiencies around a percent or higher per nucleotide. The crude product is purified by high-performance liquid chromatography or PAGE and may be labeled for detection. Short oligos are susceptible to nuclease degradation and are commonly stored under appropriate conditions to preserve stability.

Other contexts: In peptide chemistry, a 12-mer refers to a peptide consisting of 12 amino acids and is used in epitope mapping or binding studies. In materials science, 12-mer polymers or oligomers are studied to investigate sequence-defined polymers, self-assembly, and structure–property relationships. The term can also appear in broader discussions of oligomer length, where 12 units balance manageability with functional complexity.