Aptamers are nucleic acid molecules that selectively bind to target compounds. Compared to antibodies, they offer a variety of benefits such as low cost of production, high stability, and ability to be used in non-physiological conditions. These properties make aptamers attractive for the development of electrochemical biosensors. One key step in discovering high-affinity aptamers is effective isolation of the aptamer-target complex from non-binding DNA in a randomized DNA library, for enrichment in the SELEX (systematic evolution of ligands by exponential enrichment) cycle. Size exclusion chromatography (SEC) was used as a means of separating aptamer-target complexes from free aptamers in the selection cycle for high affinity aptamers. Specifically, this separation mechanism targets aptamers that contract in size upon binding target compounds. As an example, the thrombin-binding aptamer (contracting into a g-quadruplex structure in the presence of potassium) was tested for isolation from other nucleic acids using SEC. This aptamer was also used as a test case for developing electrochemical biosensors, where the aptamer’s conformational change can be converted to a change in current flow. A second aptamer, targeting L-tyrosinamide, was also tested. In the future, SEC-SELEX will be used to select novel aptamers for small molecules such as 3-hydroxykynurenine (3-HK), a toxic metabolite of tryptophan whose upregulation has been seen in several neurodegenerative diseases.

Size exclusion chromatography-based selection of structure switching aptamers for electrochemical biosensors

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.