Both antibodies and aptamers bind to a wide range of biological targets, from small molecules to proteins to whole cells, with a high degree of specificity and selectivity.
Antibodies have a richly researched history in biochemical detection. They are produced by an animal inoculated with the target (polyclonal antibodies) or a specific cell line derived from a target-immunized animal (monoclonal antibodies).
Aptamers are a more recent addition to the world of biosensors. First discovered in 1990, aptamers are short oligonucleotides selected against a target molecule by a process called SELEX: systematic evolution of ligands by exponential enrichment, where molecules with the highest affinity are selected through rounds of mutation and selection.
Both antibodies and aptamers are interesting candidates when developing a diagnostic assay:
Comparison of Detection Assay Advantages/Disadvantages
|
Antibodies |
Aptamers |
|
Applicability in diagnostics well researched and documented |
Burgeoning in biochemical diagnostics field |
|
Produced relatively quickly |
Long and labour-intensive SELEX process |
|
Target molecules that do not generate immune response must be conjugated to carrier (e.g., BSA) |
Immune response not required |
|
Costly to produce each batch |
Cost-effective production once sequence in known |
|
20 amino acids with a wide range of functionalities/interactions |
Only 4 natural nucleotide bases with similar functionalities/interactions |
|
Variability between production sources/batches |
Highly reproducible manufacturing |
|
Highly sensitive to storage conditions/freeze thaw cycles |
Much more stable, no freeze thaw degradation |
|
Specific buffers required for stability |
Stable stored in water |
|
Easily conjugated to enzymes, fluorescent molecules, etc. for detection |
Location-specific 5’ or 3’ functionalization possible (e.g., thiol for gold conjugation, biotin, amine, fluorescent molecule) |
|
Antibodies for novel targets typically not commercially available |
Easily produced the moment sequence is available in scientific literature |
Overall, antibodies and aptamers have unique advantages and disadvantages. Depending on the requirements of the assay, one recognition element may be better suited. It is also possible to use both antibodies and aptamers within the same assay!
Contact us for more information regarding which recognition element to use for your assay development.