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Oligonucleotide-aptamer Conjugation Service

Aptamers refer to small nucleic acid ligands that exhibit specific therapeutic functions and an unambiguous binding affinity for their targets, and they may serve as delivery agents for therapeutic oligonucleotide and facilitate long-term therapeutic efficacy and safety. With over ten years’ extensive experience and advanced platforms in oligonucleotide conjugation, Creative Biolabs can offer high-quality oligonucleotide-aptamer conjugation service by using the raw materials provided from our customers.

Introduction of Oligonucleotide-aptamer Conjugation

Aptamers are a class of small nucleic acid (typically 20-100 nucleotides in length) ligands composed of single-stranded DNA or RNA oligonucleotides that fold into specific 3D structures and bind to various molecular targets with high specificity and affinity. Aptamers possess unique chemical and biological characteristics determined by their nucleotide sequence and exhibit bioactivities comparable or superior to that of antibodies. Therefore, aptamers have become a promising new class of molecular ligands more suitable for the development of novel clinical applications. Although their small size makes aptamers susceptible to kidney filtration and short circulation time in vivo, rational chemical modifications and conjugations can improve their pharmacokinetic properties of aptamer-based therapeutics.

Small interfering RNA (siRNA) and microRNA (miRNA) molecules are powerful gene-silencing tools that represent a new class of gene-mediated therapeutics. However, a major obstacle in the use of siRNAs in clinical applications is the efficient delivery to the intracellular space in vivo due to their lack of cell/tissue specificity. Therefore, a combination of siRNA/miRNA technology with aptamers of particular targeting can achieve selective gene targeting with high efficiency and deliver siRNAs or other therapeutic oligonucleotides to the cell.

Oligonucleotide-aptamer conjugation. Figure 1. Oligonucleotide-aptamer conjugation. (Zhou, 2017)


Conjugates with an aptamer and an oligonucleotide part can easily be prepared by chemical synthesis and coupling of oligonucleotides. One primary approach has been developed to prepare covalent chimeras of oligonucleotides with aptamers that target specific proteins. Typically, a strand of the siRNA linked to the aptamer is synthesized by in vitro transcription and complexed by hybridization. Another effective strategy is accomplished through a simple and straightforward hybridization reaction: the aptamer and siRNA portions are hybridized using a short complementary sequence appended to the ends, such as GC-rich sticky bridge sequence. Such conjugates or chimeras can be easily and naturally formed by transcription or simple hybridization. This simple conjugation did not affect the biological functions of either the aptamer or the siRNA. Through either covalent fusion or non-covalent assembly, a large number of aptamers have been successfully conjugated with various therapeutic oligonucleotides to achieve targeted delivery.


Aptamer-mediated delivery of siRNA. Figure 2. Aptamer-mediated delivery of siRNA. (Barbas, 2010)

Applications of Oligonucleotide-aptamer Conjugation

Targeted oligonucleotide-based drugs (e.g., siRNAs, miRNAs, shRNAs) have been developed for multifarious diseases, including cancer, HIV, and indications of the immune system. One of the critical impediments in the development and clinical application of siRNA and other nucleic acid-based pharmacological agents is their delivery to both systemically and to specific cell or tissue types. To overcome these obstacles, aptamer selectively targeting a specific protein or cell surface is utilized as specific drug delivery vehicles to deliver siRNAs-based targeted therapeutics or other therapeutic cargoes into cells, at the same time, it increases binding affinity and improves the therapeutic effect. Exploiting the power of therapeutic siRNA drugs and efficient delivery techniques has significant potential for the treatment of various human disease conditions.

The high specificity and functional versatility of aptamers have made them very useful for applying in many aspects of diagnostic and therapeutic applications, such as improving the delivery efficacy of a variety of oligonucleotide therapeutics. With years of experience and comprehensive platforms in oligonucleotide conjugation, Creative Biolabs has gained significant knowledge and is confident to provide oligonucleotide-aptamer conjugation service to meet our customers' specific requirements all over the world. Please do not hesitate to contact us for more details.


  1. Barbas, A.S.; et al. (2010). Aptamer applications for targeted cancer therapy. Future Oncology. 6(7): 1117-1126.
  2. Zhou, J.; Rossi, J. (2017). Aptamers as targeted therapeutics: current potential and challenges. Nature Reviews Drug Discovery. 16(3): 181.


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