Another practical application for aptamers is as a replacement for antibodies in conventional histology and molecular imaging. Both directly and indirectly labeled aptamers have been used to detect individual receptors or to differentiate cancerous from non-cancerous cells.
One of the key advantages of aptamers is their ability to be synthesized with modifications for conjugation, covalent coupling, fluorescent reporting and more — with no impact on performance. Our engineering techniques have successfully produced aptamers for a range of applications. Some examples include:
Aptamers have a proven capacity to perform in western blot and dot blot applications. They can also function as direct replacements for antibody reporters in Enzyme-Linked Immunosorbent Assays (ELISAs).
A number of conjugation/functionalization modifications are used to engineer aptamers for this purpose. The simplest approach involves synthesizing the DNA or RNA strand to contain either a 5’- or 3’-fluorophore option. Base Pair Biotechnologies also has considerable experience conjugating aptamers to quantum dots, providing a higher quantum yield and larger Stokes’ shifts of fluorescence as photons are absorbed and emitted.
For additional signaling, aptamers can be synthesized with a 5’- or 3’-biotin and detected by a streptavidin/horseradish peroxidase conjugate (strep-HRP). Numerous commercial sources for both fluorescent and chromagenic HRP substrates are available. This approach is commonly referred to as an “ELONA” or aptamer-ELISA (“ELASA”).
By synthesizing aptamers with a terminal biotin or amino group, our scientists can engineer reagents that readily couple with beads or nanoparticles. Such functionalized particles have been used to concentrate transcription factors or, in the form of magnetic beads, to enrich bacterial pathogens or cancer cells. These reagents could potentially be used to develop highly multiplexed bead-based assays such as Luminex/Magpix.