A fluorescence-readout method for miRNA-155 detection with double-hairpin molecular beacon based on quadruplex DNA structure

Complete analysis of profiling biomarkers paves the way for the early diagnosis of fatal diseases and also increases the chances for successful treatment and patient survival. So the rapid and ultrasensitive detection of miRNA, as an important biomarker for cancer detection, has great importance. Herein, we developed a new approach based on label-free double-hairpin molecular beacon (DHMB) for the detection of miRNA-155. The proposed DHMB probe had two distinct loops that are responsible for target recognition and signal transduction, respectively. Upon the addition of miRNA-155, the locked regions of DHMB were released. The free G-rich sequence is able to form a G-quadruplex structure and bind with Thioflavin T (ThT) for a specific fluorescent response. The Sensitivity investigation indicates that the fluorescent intensity of G-quadruplex increased within a dynamic range of (1.02 x 10(-9) to1.44 x 10(-7) M M) after the addition of miRNA-155 as the target.. Also, the proposed biosensor exhibits excellent specificity toward miRNA-155 with a detection limit of (LOD) 0.18 x 10(-9) M and showed satisfactory results in human serum spiked test.