Aptamers vs antibodies
What are the differences and advantages ?

Aptamers and antibodies play a central role in diagnostics and analytical assays. Their high binding specificities make them tools of choice for quantitatively detecting molecular targets in various samples (tissue, blood, water, food,…). They are widely used for biosensing in association with different modalities of signal transduction (fluorescence, colorimetry, electrochemistry). They enable the quantitative specific detection of the target molecule in the field through simple, cheap and rapid assays.

Aptamers and antibodies play a central role in biomedical research and medical practice. Their high binding specificities make them tools of choice for detecting and identifying specific molecular targets in biological samples.They are widely used in diagnostic tests, biomarker discovery, protein characterization and understanding the mechanisms underlying disease.
In medicine, monoclonal antibodies are used to treat certain autoimmune diseases and certain types of cancer. Aptamers, on the other hand, offer a promising alternative, notably as vectors for targeted drugs and personalized medicine.

The aptamer selection process, or SELEX, lies at the heart of the identification of specific aptamers. It begins with the synthesis of a random oligonucleotide library in which each sequence has a unique three-dimensional structure. This library is then subjected to selection cycles that include binding to the target, washing to remove unbound sequences and recovery of target-bound aptamers. This process is repeated many times until aptamers with high specificity and affinity for the target are selected.

Specific binding mechanism

Aptamers form hydrogen bonds, electrostatic interactions and Van der Waals interactions with the target. This enables highly specific binding between the aptamer and its target, depending on the latter’s precise molecular characteristics. The three-dimensional conformation of the aptamer is crucial, enabling it to adapt perfectly to the shape of the target, thus providing the specificity of the binding.

Applications in research and medicine

The ability of aptamers to bind specifically to molecular targets makes them valuable tools for biomarker detection, protein characterization, drug and contaminant analysis and the understanding of biological mechanisms. They are also used to specifically target tumor cells or virus-infected cells, paving the way for targeted treatment possibilities. In research, aptamers are used to study protein interactions, identify binding partners and explore cell signaling networks

One of the major advantages of aptamers over antibodies is their high specificity. Aptamers are identified in the laboratory through positive and negative screening in order to discriminate between closely related targets.
The SELEX selection process generates aptamers that bind tightly and specifically to the target, minimizing non-specific binding to other molecules in the sample. This specificity guarantees greater precision in the detection and quantification of molecular targets, and reduces the risk of false positives and false negatives.
· Versatility of aptamers : Aptamers are obtained by chemical synthesis on solid support. Chemical modifications can be introduced at will at given sites in order to provide them with additional properties depending on the application (increased lifetime, detection by fluorescence, immobilization on a biochip, …).
· Thermal stability of aptamers : Heating aptamer solution to 80-90 °C will denature them.
However, unlike proteins, they will refold upon cooling and regain their functionality.

Cost advantage for aptamers

The large-scale production of monoclonal antibodies requires the development and maintenance of hybrid cell lines, which is extremely costly. What’s more, antibody production requires specialized facilities and thus a major investment in material resources.

In contrast, in terms of production costs, aptamers offer a significant advantage over antibodies. Morever the chemical synthesis of aptamers, including under GMP conditions, ensures a guaranteed sourcing, no batch no batch variability.

Our partnership with Eurogentec

Eurogentec provides oligonucleotide products and services to scientists involved in life science research, molecular diagnostics and therapeutic development. An expert in both small- and large-scale synthesis, Eurogentec produces a wide range of customized oligonucleotides, including chemically-modified ones (nuclease resistant backbones, modified nucleic acid bases, end-conjugated sequences).
Novaptech and Eurogentec have signed a partnership agreement for the production of aptamers selected by Novaptech. https://www.eurogentec.com/en/search?q=novaptech

Low/no immunogenicity of aptamers

Another major advantage in the antibody vs aptamer match-up lies in the low or even absence of immunogenicity of aptamers compared with antibodies.