Design Strategies and Applications of Signaling Aptamers

Signaling aptamers are aptamer probes that couple molecular recognition to signal transduction. Aptamers do not have signaling capabilities when they are isolated from random-sequence libraries and can be engineered into singal reporters by rational design based post-selection modifications. The existing rational design strategies can be divided into two groups:labled and labled-free signaling aptamers. Different signaling strategies of using one fluorophore labeled aptamers based on fluorescence polarization assay, dual labeled aptamers based on fluorescence resonance energy transfer such as molecular beacon aptamers, structure-switching signaling aptamers and in situ labeled aptamers, or other labeled-free aptamers incuding chimeric aptamer approach, substitution approach, light-switch complex approach and aptamer-polymer conjugate approach are reviewed. In vitro selection approach for generating aptamers that can be immediately transformed into effective signaling probes without the need for further optimization is also described. These singaling aptamers can be a useful tool for the development of biosensors and homogeneous assays especially in real time protien recognition and quantitation which do not require multiple immobilisation or washing steps.