Novel One-Shot Fluorescent Aptasensor For Dengue Fever Diagnosis Using Ns1-Induced Structural Change Of G-Quadruplex Aptamer

In this study, we proposed a new G-quadruplex (GQ)-based fluorescent aptasensor using one-shot detection of NS1 for dengue fever diagnosis. To design the aptasensor, Dengue virus-derived NS1-binding aptamer (DBA) that forms a GQ structure was developed. The DBA underwent structural destruction induced by nonstructural protein 1 (NS1), then we aimed to utilize it for optical sensing. Fluorescent detection of the NS1-dependent structural change was performed by applying a fluorescent dye; 6-carboxyfluorescein (FAM) was attached to the 5' end of DBA (5' FAM-DBA). The 5' FAM-DBA could quantitatively detect the fluorescence quenching caused by guanines upon NS1 binding, which was feasible for dengue fever diagnosis. We analyzed to understand the structural and fluorescent characteristics that are involved in the interaction between NS1 and DBA. The results suggested that the central G-tracts were rearranged to adjacent toward the FAM, and that the structure of 5' FAM-DBA bound to NS1 was expected to form base-pairing. Finally, the aptasensor with 5' FAM-DBA was established after optimization, which contributed to the effective and rapid detection. The aptasensor achieved low detection limits of 2.51 nM in buffer and 8.13 nM in serum. Additionally, it was verified the high specificity using other proteins including yellow fever proteins, and it has the potential to overcome the cross-reactivity with other flaviviruses. Also, the stability of the DF aptasensor was confirmed to give practical usability. Here, we developed a novel GQbased fluorescent aptasensor for rapid and simple dengue fever diagnosis, which could provide the possibility for use in practical applications.