25th August, 2017

Starting with the end in mind

The use of aptamers in point of care diagnostic devices, for monitoring drug dose levels or for use as therapeutics, requires functionality across a wide variety of conditions.

Aptamer selection starts in conditions optimised to promote aptamer/target interaction to identify the best target-binders. Subsequently, by introducing different pressures, we are able to drive aptamer selection in a manner similar to directed evolution. To enable this we introduce the required end use media into the selection process, isolating the aptamers that will perform preferentially for the final application.

Examples of complex environments that we have selected aptamers to function in include sweat, sea water, elevated temperature (37oC), cell extracts and plasma.

Aptamers in Plasma

A recent customer project required the selection of aptamers to a cancer therapeutic in human plasma. This media presents a range of challenges which needed to be accounted for.
Monoclonal data for aptamer selection in complex media

This chart shows the amount of aptamer recovered, comparing non-specific elution to target-specific elution. The ‘Starting library’ has not been enriched and shows no difference in the quantity of bound aptamer when the target is introduced. The ‘Aptamer population’ is an enriched polyclonal pool of aptamers from the later stages of selection. From here we wanted to find the best binding monoclonal aptamers, which are shown as ‘Aptamer 1’ and ‘Aptamer 2’.

The amount of target binding aptamer is not the only aspect we need to consider. Another deciding factor is the amount of non-specific binding. In this selection, Aptamer 2 was selected as it has the greatest ratio of target-specific to non-specific elution.

If you would like to discuss the possibility of incorporating aptamer technology into your research, discovery or development projects please contact us using the form below.