Aptamers: The ‘‘evolution” of SELEX
It has been more than two decades since the first aptamer molecule was discovered. Since then, aptamer
molecules have gain much attention in the scientific field. This increasing traction can be attributed to
their many desirable traits, such as 1) their potentials to bind a wide range of molecules, 2) their malleability,
and 3) their low cost of production. These traits have made aptamer molecules an ideal platform
to pursue in the realm of pharmaceuticals and bio-sensors. Despite the broad applications of aptamers,
tedious procedure, high resource consumption, and limited nucleobase repertoire have hindered aptamer
in application usage. To address these issues, new innovative methodologies, such as automation and
single round SELEX, are being developed to improve the outcomes and rates in which aptamers are
discovered.
Automated SELEX
Automated SELEX methods are characterized by the ability to
perform multiple SELEX cycles without supervision, intervention
or manual manipulation. Advantages of this method include: 1)
increase the number of selection rounds per day and 2) multiple
selections can be done in parallel. Automated SELEX method
designs hinge on either a larger scale liquid-handler based design
(that relies on a small volume liquid-handler robotics platform
with various modifications and attachments to complete each
step), or a microfluidic centered paradigm [37]. Liquid-handler
based automated SELEX platforms have been widely reported.
Cox et al. utilized a Biomek 2000 platform modified with a thermocycler
and a filtration module to isolate RNA aptamers [38,39]. This
platform has been cited as the basis for multiple subsequent automated
selection attempts for such targets as amyloid fibrils [40],
the virus causing foot and mouth disease [41] and PSA [42].