The new RNAi-cap for potent miRNA mimics
The RNAi-cap® for miRNA mimics: what is it exactly?
Riboxx has invented and validated a new design for miRNA mimics (Fig. 1) . So far, miRNA mimics offered by all other companies are duplex RNA with 3´-overhangs or blunt ends. The miRNA mimics design invented at Riboxx features the new RNAi-cap technology, as shown in Fig. 1
The miRNA mimics designed by Riboxx is a blunt-end siRNA of 24 bp in length. It has at the opposite of the SEED region the RNAi-cap that is a strecth of 5x[C/G]s.
Fig. 1. Riboxx design for potent miRNA mimic with the new RNAi-cap. The RNAi-cap is located at the opposite side of the SEED-region, as indicated. The miRNA mimics with the RNAi-cap is 24 bp in length and has blunt ends.
Benefits of the RNAi-cap
The RNAi-cap increases the stability of the duplex at the opposite of the SEED region, as it consists of a stretch of G and Cs perfectly annealed.
As a consequence, the RISC unwinds the duplex at its less stable end, meaning where no RNAi-cap is present. This leads to increased loading of the guide strand to the RISC. The passenger strand is then discarded, and off-target effects reduced.
Additionally, the RNAi-cap offers the benefit that much less miRNA mimics is needed for an effective gene silencing with a further reduction of off-target effects .
Moreover, because the duplex is more stable, it has an improved stability of miRNA duplex with subsequent improved half-life in body fluids.
 Nolte A, Ott K, Rohayem J, Walker T, Schlensak C, Wendel HP. Modification of small interfering RNAs to prevent off-target effects by the sense strand. N Biotechnol. 2013 Jan 25;30(2):159-65.