Custom Aptamer Synthesis

Aptamers are very useful in biotechnology and therapeutic applications because they have molecular recognition properties comparable to antibodies. In addition to differential recognition, custom aptamers have advantages over antibodies because they can be fully engineered in vitro, are easily generated by chemical synthesis, have desirable storage properties, and have little or no immunogenicity in therapeutic applications. BOC Sciences offers aptamer customization services to generate high-quality aptamers tailored to your goals, delivering excellent results even for the most difficult target molecules.

Fig 1. Different types of modifications in aptamers. (Srivastava et al., 2021)

What is Aptamer?

Aptamers are single-stranded DNA or RNA oligonucleotides (ssDNA and ssRNA), typically 20 to 80 nucleotides in length, with molecular weights ranging from 6 to 30 kDa, that fold into a unique 3D conformation. Nucleic acid aptamers are sequence selective, fold specifically and bind to selected molecules or targets. The single strand of the nucleic acid aptamer folds into a well-defined three-dimensional (3D) structure. The target molecules recognized by nucleic acid aptamers can be small molecules such as cocaine as well as proteins and peptides or other molecules. Nucleic acid aptamers allow the design of reagents with high affinity for the desired compound or molecule.

Characteristics of Aptamers

• High affinity for the target molecule.
• Aptamers are readily available, can be synthesized in vitro in large quantities and quickly, and are simpler to prepare.
• Aptamers can be screened against different kinds of targets, which broadens the scope of application.
• High stability and favorable for storage.

Custom Synthesis of Aptamer

If the oligonucleotide sequence of the nucleic acid aptamer is known, it can be produced using chemical solid phase oligonucleotide synthesis. In turn, nucleic acid aptamer synthesis can be achieved using DNA, RNA or modified nucleic acids. Both chemical and enzymatic aptamer synthesis are possible, and the combination of the two will also produce specific aptamers. Aptamers can bind to their targets with high affinity through van der Waals forces, hydrogen bonding, electrostatic interactions, stacking of flat portions and shape complementarity.

• Aptamer Preparation Steps

1. Prepare an initial oligonucleotide library containing approximately 1014 to 1015 random sequences with a length of 30 to 50 nucleotides between two primer binding sites.

2. During incubation, the random sequences in the initial pool fold into different secondary and tertiary structures and form aptamer-target complexes under optimal conditions.

3. Separation: The unbound sequences are separated from the target-bound sequences using methods such as membrane filtration, affinity columns, magnetic beads, or capillary electrophoresis.

4. Amplification: The DNA consortium amplifies the target-bound sequence by PCR and the RNA consortium amplifies the target-bound sequence by RT-PCR. The reaction products are used as new aptamer libraries for the next round of screening.

5. The enriched aptamer sequences are sequenced using Sanger sequencing or newer high-throughput sequencing methods.

Services Contents

• Custom DNA Aptamer Synthesis
• Custom RNA Aptamer Synthesis

Aptamer Characterization

• Affinity Determination

Affinity measurements can be performed using Surface Plasmon Resonance (SPR), Bio-Layer Interferometry (BLI), to evaluate the binding strength and affinity of Aptamer to its target molecules.

• Selectivity and Specificity Assessment

The selectivity and specificity of Aptamer can be determined by our research team by evaluating the cross-reactivity between Aptamer and its target and similar molecules using competition binding assays.

• Stability Assessment

BOC Sciences can use stability assessment to determine the stability and storage suitability of Aptamer under different conditions.

BOC Sciences provides high-quality oligonucleotide products as well as custom synthesis of Aptamer, and structure and function validation of the products. If you are interested in our services, please keep in touch with us.

Reference

1. Srivastava S, et al. Aptamers: An emerging tool for diagnosis and therapeutics in tuberculosis[J]. Frontiers in Cellular and Infection Microbiology, 2021, 11: 656421.