23rd April 2019

We have often shown that aptamers make ideal ‘capture reagents’ for use in target specific affinity chromatography. Their flexible structure makes aptamers ideally suited for the specific binding and controlled release of their target, even in the presence of complex matrixes such as cell lysates or plasma.

During the aptamer selection process, we can tailor conditions and manipulate the aptamer population to have your desired characteristics. These can include; binding in your complex matrix (cell lysate), wash conditions to remove contaminating proteins and specific elution conditions, which are compatible with you target protein. Unlike antibody-based affinity chromatography, the aptamers require only a ‘gentle’ change in buffer conditions (+/- 1pH or 0.5M salt change) to elute the target.

It is also important that, the aptamer loaded resin can be easily regenerated. Once we have selected target specific aptamers, we immobilise the aptamers on a biosensor and test the binding, wash and release of the target over multiple cycles, using your chosen conditions, to validate the reusability of the aptamers. One example of this is shown below.

Figure 1:  Biolayer Interferometry (BLI) data showing 50 consecutive cycles of binding, washing and eluting of a target by aptamers immobilised on to a sensor surface (red trace). No binding is seen to the blank sensor (blue trace).

This data alows us to to analyse the performance of the aptamer in the customer defined conditions in real time. As you can see from the data in figure 1, during 50 cycles of binding, washing and eluting, the aptamer remains consistent in its performance. The data can also be corrected and each binding event can be overlain to show the reporoducibility of interaction over the 50 cycles.

Figure 2: Overlay of 50 repeat cycles of aptamer-target binding.

By viewing the interaction in this manner, we can easily compare the interaction between the aptamer and their target through multiple purification events.

If you are looking to optimise your downstream processing, struggling with antibody based purification or are interested in aptamers for other applications, please contact us using the form below or call +44 1904 567790.

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