Fimers are primers with proprietary chemical modifications made by Fidelity Oligos LLC that inhibit unwanted reactions during cycle sequencing (e.g., primer-dimer artifacts and non-specific PCR). Specially designed Fimers have been routinely and successfully used for high throughput sequencing of difficult templates and highly sensitive reactions from minimal amount of templates (Polushin et al., Nucleosides Nucleotides Nucleic Acids, 2001 20, 507-14). 

An example where non-specific PCR is eliminated with the use of Fimers.
Fimers Sequencing Traces
Sequencing traces obtained with the use of a 35 base-long modified (A) and non-modified (B) primer.

Fimers are primers with proprietary chemical modifications that inhibit unwanted reactions during cycle sequencing. They are prepared from oligonucleotides possessing one or more SUC precursors. By carefully selecting the position of precursor incorporation on the oligo we can select the optimal Fimers to inhibit primer-dimer extension and non-specific PCR for sequencing reactions. It has been shown that Fimers decrease the Tm of the duplex formed with its unmodified complementary strand and improve the annealing specificity, thus contributing to the suppression of non-specific PCR. Furthermore, no primer-dimer extension products were detected by placing the modified nucleotide at the -7 position from the primer 3′-end having complementary bases to itself, and high quality sequence from the template DNA was obtained.


Fidelity Oligos LLC
7965 Cessna Ave
Gaithersburg, MD 20879



Phone: 301-527-0804
Fax: 301-527-8250