Hemicyanine dyes as fluorescent probes for DNA aptasensor detection strategies
University of Guelph
Wednesday, December 1, 2021
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ABSTRACT:Functional nucleic acids can now be created in vitro that are capable of binding specific targets with high affinity and specificity. These biomolecules, termed aptamers, have been employed as versatile tools for the detection of important analytesfor applications in imaging, diagnostics and therapeutics. Common DNA aptamertopologies include G-quadruplex(GQ) DNA, which contain planar G-tetrad structures composed of four guanine bases attached via loop residues, and DNA three-way junctions (3WJ) comprised of three duplex stems with a Y-shaped hydrophobic branch-point. To turn GQ-binding events into read-out signals, the GQ recognition element is typically incorporated into a DNA nanodevicethat is capable of controlled conformational changes. Common examples include GQ‒single-strand or a GQ‒duplex equilibrium. In contrast, target detection involving DNA 3WJs is an example of host-guest biosensingin which the aptamerdoes not undergo a conformational change upon target binding. In this presentation, fluorescent strategies for aptasensordevelopment will be presented. Dye types utilized in these studies include push-pull donor-acceptor biarylsand cationic merocyaninesthat exhibit emission sensitivity to microenvironment polarity and solvent rigidity. They can be utilized free in solution (label-free) or covalently attached to the DNA aptamerat specific internal locations. On-strand strategies to incorporate biaryland merocyaninedyes into DNA aptamers, together with the pros and cons of a label-free versus a label strategy for aptasensordevelopment will be presented.