30th May 2017

Exquisite Selectivity Possible with Aptamers

At Aptamer Group we can select aptamers that bind to small molecules. This is a key differentiator from antibodies where the target needs to be immunogenic. During selection it is possible to introduce counter-selection molecules to remove aptamers that will bind to moieties closely related to the target. Counter-selection drives selectivity to the target small molecule of interest.

Case Study

The following data were generated during a recent project at Aptamer Group. The aptamer library was exposed to the target for round 1 and aptamers binding to the small molecule target of interest were amplified after each of 7 subsequent rounds to drive evolutionary selection and refinement of the binding aptamer population.

Small Molecule Target Aptamer Selection with Metabolite Counter Selection

Illustrative data presenting the concentration of ssDNA (pmol) after rounds of aptamer selection against the target of interest and counter-selection targets. Counter-selection 1 (cs1) introduced the main metabolite of the target. Counter selection 2 (cs2) introduced human plasma and metabolite.

From round 7 onwards a counter-selection molecule, the main metabolite of the target, was introduced (cs1). In this instance, the counter-selection molecule lacked only a dipiperidine group present on the target of interest. The population of aptamers binding to the target was initially reduced by the introduction of the counter-selection molecule, but then revives exponentially by round 11.

Rounds 9 to 11 were also performed with an extra condition for counter selection (cs2), human plasma (40%) plus the metabolite. With the introduction of plasma, although the concentration of counter-selection binding aptamers increased, as selection progresses the concentration of target binding aptamers also increases.

To discuss how aptamers can help you detect small molecules call us on 01904 567 790 or email info@aptamergroup.co.uk.