Others - Aptamers

I will be briefly touching on aptamers as they are gaining much attention among scientists that are developing biosensors. I guess it will be good for us to be "updated" to more "new" recognition elements.

Aptamers are DNA or RNA that can recognise and bind to specific targets. You can compare them to receptors or even enzymes because they work based on the lock-and-key relationship with their targets.

To those who have taken DDCT, you would find the technique of producing these aptamers, a.k.a Systematic Evolution of Ligands by Exponential Enrichment (SELEX), familiar.

First, there will be a library of nucleic acids to which the desired targets are introduced, allowing nucleic acid-target complexes to form. Those nucleic acids that do not bind or are weakly bound to the targets will be removed. This cycle will be repeated a few times before the sequences are amplified. You may think of this step as a stringent selection of the best. Amplification is performed by PCR for DNA sequences and RT-PCR for RNA sequences.

RT-PCR may be new to some of us and so, if you are keen, more information can be found in some of the posts by Tiong Han (1 - brief intro & protocol, 2 - RT-PCR probes), Jess (3 - pictures) and myself (4 - intro).

Some consider aptamers better than antibodies (another recognition element) because SELEX typically take 8 weeks or less while antibodies can take up to months! In addition, aptamers also have a wider range of targets because they can differentiate the chirality and structure of molecules. It's no wonder they are gaining so much attention!

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