Oligonucleotide Synthesis for AOC Development

Synthetic oligonucleotides (ONs) have been investigated for various therapeutic and diagnostic applications. The interest in ONs arises because of their capability to cause selective inhibition of gene expression by binding to the target DNA/RNA sequences through different mechanisms. Creative Biolabs is a leading biotechnology company that has the expertise and ability in providing ON synthesis, modification, and conjugation services for customers worldwide. Armed with sophisticated equipment, advanced antibody conjugation technologies, and highly experienced staff, we now provide customized ON preparation service for antibody-ON conjugates (AOCs) development.

ONs Introduction

ONs are chemically synthesized short nucleic acid sequences (DNA or RNA), which have the selective inhibition of gene expression by interfering with the flow of information in biological systems, resulting from their binding to the target sequence by a variety of mechanisms such as antigene or triplex approach, antisense activity, and RNA interference (RNAi). The two most important parameters of ONs are their length and composition. These two parameters define the majority of the features and functional properties of ONs. To date, ONs have become vital for many commonly used laboratory techniques, including polymerase chain reaction (PCR), DNA sequencing, and array preparation. Since the discovery of small interfering RNA (siRNA), there have been over 60 clinical trials and the first drug patisiran (Onpattro) was approved for use in the clinic in 2018.

Fig.1 Therapeutic ONs act on different stages of pathological gene expression. (Takakura, 2019)

Recently, ON conjugate has attracted increasing attention, owing to its obvious advantages of improving the existing ON properties and imparting entirely new properties. ONs are conjugated mostly at 5’- or 3’-termini because of their easy accessibility. The 2’-positions of ribose sugar, nucleobases, and internucleotidic phosphodiester bonds can also be used for conjugation. Studies have proved that conjugation through the 3’-terminus enhances the exonuclease resistance and the 2’-OH modification has been found particularly useful in an antisense strategy. Several synthetic approaches have been developed for facile preparation of ON-conjugates, which can be grouped into two major categories: (i) on-support conjugation, where conjugation is achieved using support-bound ONs; and (ii) solution-phase conjugation, where ONs are cleaved from the support, deprotected and purified, before solution-phase conjugation.

Fig.2 Structures of natural and modified ON backbones. (Singh, 2010)

What Can We Do for You?

Tremendous efforts have been made by Creative Biolabs to improve the ON properties by either incorporating chemical modifications in the ON structure or covalently linking reporter groups to ONs. We have developed a large number of ONs containing modified sugars, bases and also evaluated their effects on intrinsic ON properties. Moreover, problems like poor stability can be resolved by introducing structural modifications in the ON structure. The poor cell or tissue-specific delivery of ONs can be addressed by conjugating natural or modified ONs to molecules such as antibodies or their fragments. The choice of the appropriate format for an ON is usually defined by the desired functionalities and current limitations of the envisioned application. With deep understanding of this, Creative Biolabs is capable of designing and synthsizing appropriate oligonucleotides.

Tips for the Design of ONs

• The amino or thiol modification should be located at either the 5’ or 3’ end of the ON. The 5’ end tends to be the preferred location as it results in higher purity ONs, which in turn slightly increases antibody-ON conjugation efficiency.
• Avoid stretches of more than four consecutive G bases since these sequences can form G-quadruplex or cruciform structures, which can result in lower hybridization and coupling efficiencies.
• Minimize base repetition.

ONs and their synthetic alternatives have been under active investigation for more than 60 years. They are not only limited to therapeutics but also found various use in diagnostics and nanotechnology. Creative Biolabs provides customized oligonucleotide synthesis and modification services for our honor clients. Further conjugation services are also available for you. If you are interested in our ON module or Conjugation Strategies for AOC Development, please feel free to contact us for more information.

References

1. Takakura, K.; et al. The clinical potential of oligonucleotide therapeutics against pancreatic cancer. International journal of molecular sciences. 2019, 20(13): 3331.
2. Singh, Y.; et al. Recent developments in oligonucleotide conjugation. Chemical Society Reviews. 2010, 39(6): 2054-2070.

For Research Use Only. NOT FOR CLINICAL USE.