DNA Photonic Nanowires for Homogeneous Entropy-Driven Biomolecular Assay of Thrombin

Inspired by the specific optical properties of DNA photonic nanowires (PNs) on which fluorescent dyes are to be precisely positioned and photonic energy transfer over nanometers can be achieved, herein, we develop a DNA PN-based homogeneous entropy-driven biomolecular assay (HEBA). Using homogeneous Förster resonance energy transfer (FRET) of Cy3, we constructed a DNA PN capable of transferring energy from the green donor dye (FAM) to the red acceptor fluorophore (Cy5) across a total distance of 10.2 nm with an end-to-end transfer efficiency of 13.2%. By taking DNA PNs as the substrate of entropy-driven circuit, thrombin was detected as a proof-of-principle target. The trigger of HEBA by thrombin, during which separation of Cy3, FAM, and Cy5 occurred and the FRET of the PN got interrupted, resulted in a high value of signal-to-background ratio (S/B, signal and background were FFAM/FCy5 in the presence and absence of thrombin, respectively), giving a detection dynamic range of 5–25 nM with a detection limit of 2.7 nM. This strategy offers an alternative platform for biomarker clinical diagnosis, greatly expanding the application fields of DNA PNs to analytical chemistry.