Solution‐Based Biophysical Methods for Guiding Design of Aptamers into Electrochemical Biosensors

Structure‐switching aptamers are utilized in various applications and have increasingly been translated into electrochemical biosensors, largely thanks to post‐SELEX sequence engineering through computational and enzymatic approaches. In the context of sequence engineering, it is envisioned that folding and binding thermodynamics could likewise contribute to accelerating translation of aptamers into sensors. Herein, this is explored by first characterizing a series of quinine‐binding aptamers using the biophysical methods isothermal titration calorimetry and nano differential scanning calorimetry. The folding and binding thermodynamics obtained are compared with the resulting analytical performance when aptamers are adapted into sensors. The findings show that the magnitude of sensor response is strongly correlated with aspects of the binding and unfolding thermodynamics of the aptamer as measured in solution. Using a similar approach, a recently reported adenosine monophosphate aptamer is successfully engineered to support electrochemical sensing. It is envisioned that relying on solution‐based biophysical methods will further improve post‐SELEX sequence engineering.