siRNA synthesis has been globally recognized as one of the most effective ways for the silencing of target genes in cells or body, and is widely accepted due to its low cost and high transfection efficiency.

The well-known siRNA synthesis is not only the optimum method for RNAi‐based clinical treatment, but also irreplaceable in drug development.

In collaboration with Cohesion Biosciences (http://www.cohesionbio.com/), Bio Basic Asia Pacific now provides two types of siRNA products, standard siRNA and chemically-modified siRNA, with various modifications of siRNA available in accordance to our customer’s requirements.

1. Standard siRNA product

The single/unpaired strands in standard siRNA products provided by us have been completely removed via HPLC method. They can be used directly in experiments after dilution with the buffer provided. The standard siRNA products directly target the mRNA of interest; therefore, it is recommended to detect the expression level of the target mRNA by real-time PCR to ensure the effectiveness of siRNA products.

2. Chemically modified siRNA

Bio Basic Asia Pacific provides a wide variety of chemically modified siRNA products, such as 2’-hydroxymethylation modification, Phosphorothioate modification, Fluoro modification, etc.. With advanced technology for siRNA synthesis, our production team has addressed the concern of siRNA stability in transfection experiments via chemical modification.

To enhance the siRNA stability, the four ends of the double stranded siRNA were labeled with fluorescent markers. As compared to unlabeled siRNA, the labeled siRNA shows the advantage of high visibility during transfection process. The labeled siRNA can be easily observed by the use of flow cytometry, fluorescence microscope, laser confocal microscope and so on. This leading technology is not only advantageous in optimizing the transfection conditions and intracellular localization of siRNA, but also in tracing and analyzing the relationship between the transfection efficiency and protein expression during the whole transfection process.

List of Modifications

Terminal Modification Base Modification
5′ FAM 2′ Fluoro dU
5′ Biotin 2′ Fluoro dC
5′ Amine 2′ OMe rU
5′ Phosphate 2′ OMe rC
5′ Thiol 2′ OMe rG
5′ Cholesterol 2′ OMe rA

Comparison Between Standard siRNA and Chemically-modified siRNA

Challenges Standard siRNA Chemically-modified siRNA
siRNA Degradation The non-modified standard siRNA is easy to be degraded in cell culture processes. Although it is effective in most in vitro experiments, its stability is poor in cell cultures The chemically-modified siRNA not only increases its stability in serum and cell culture, but also strengthens its in vitro application capability
Effective Period Relative short effective period, approximately one week under normal circumstances The chemically-modified siRNA has longer effective period, its effective time is twice as that of the standard siRNA
in vivo Activity The standard siRNA has poor stability, usually is not applicable to in vivo experiments The chemically-modified siRNA has strong stability in vivo

Ordering Information

Product Information Final Yield Purification Turnaround/Lead Time
Standard siRNA 2 – 250 OD HPLC 6 – 15 Working Days
Chemically-modified siRNA 5 – 250 OD

*Price (SGD): Pricing may vary depending on desired final yield and purification method

For ordering or request of quote, kindly provide us the following information and email to sg@biobasic-asia.com:

  • Gene sequence/ GeneID or Accession Number
  • Sequence sense (5′-3′)
  • Sequence antisense (5′-3′)
  • Chemical Modification (if any)
  • Fluorescent Label (if any)
  • Special Modifications (if any)
  • Desired Quantity (OD/nmol)


Upon the completion of project, we will provide:

  • siRNA products in customer’s desired scale and purification
  • Delivery reports that contain the siRNA oligo name and sequence; concentration; the precise number of OD and nmols; Tm; MW; Size; extinction coefficient and purification type.

Storage and Stability

Although oligonucleotides are stable in solution at 4°C for up to 2 weeks, recommended storage condition should be at -20°C. Repetitive freeze-thaw cycles should be avoided by storing as aliquots. Storing at concentrations above 20uM is recommended. We guaranteed the quality of oligonucleotides for 6 months upon receipt, if stored under the above conditions.