Aptamer Chemistry Series II : The Adapter

At NeoVentures we are global leaders in the development and application of chemistries that enable aptamer performance in diagnostic devices. Usually I start my blogs with a cultural analogy, sorry to disappoint with the adapter image this time. The reason for the analogy is to move beyond the specifics of the example and provide a broader context for the general thought behind the process. In this case, as you will see the best analogy is an adapter, the adapters that we are always searching for to connect everything.

In this case the adapter is cyanuric chloride and the two ends that we are connecting are primary amines. Cyanuric chloride has three chloride atoms attached to a 1,3,5 triazine ring.

One of these chlorides is reactive to a primary amine at low temperature ~ 4C. We use this to attach the cyanuric chloride to a primary amine on the end of an aptamer. Another chloride is reactive at a higher temperature, 30 – 40 C. We use this to react the aptamer/cyanuric chloride molecules to polyethylenimine (PEI).

We obtain consistently high yields with this approach, and it is possible to load a lot of aptamer on a small amount of PEI. As shown in the diagram, the PEI that we use has four primary amines per repeating group within the polymer, and there are over 200 repeating groups per polymer. There is a caution however, the chemical reaction must be done under controlled conditions in a fume hood, the pH must be maintained above pH 8.3 in order to ensure that no hydrogen cyanide is made as an off-product. We find that PEI passively immobilizes well to a large number of surfaces. This approach enables us to increase the amount of aptamer loaded as capture in lateral flow and ELISA over the use of biotin and streptavidin.

If you are interested in a free consultation regarding your potential application with aptamers and to learn what chemistries work well please let us know. Remember aptamers are not antibodies and we need to invent and use different chemistries in order to enable them to be competitive.

The adapter image may not seem like an artistic reference but then Andy Warhol, and before him Marcel Duchamp argued that everything is art. In many ways aptamer development and application is still an art, we are focused on learning the principles behind our successes and our failures and transforming this from an art into something more beautiful, a science

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