A stretching-state DNA triangular prism based electrochemical biosensor for rapid and sensitive microRNA detection

Although microRNA (miRNA) electrochemical biosensors usually depended by specific DNA capture probes, their slow hybridization rate at the interface leads to inefficient hybridization kinetics and reduced binding efficiency, thereby prolonging the detection process and hindering rapid detection. To overcome this limitation, a stretched DNA triangular prism capture probe (TPCP) is screened and verified through the metal-enhanced fluorescence, and then employed in the development of an electrochemical biosensor for miR-21 rapid detection. The TPCP is assembled via four ssDNA in a single step, providing simple synthesis, structural stability, and high overall rigidity. It not only enhances the synthesis efficiency of TPCP, but also increases the utilization rate of the electrode surface, which improvs the capture efficiency and detection sensitivity of the target miR-21 simultaneously. The results demonstrate that the TPCP biosensor achieved ultra-rapid and highly sensitive detection of miR-21 within a wide linear range from 100 aM to 100 nM, and a detection limit of 37.97 aM in 40 min. Furthermore, the biosensor exhibited remarkable accuracy and stability when detecting miR-21 in serum samples and cell lines. In summary, this biosensor offers ultra-rapid and highly sensitive detection of miRNA and holds great promise for application in the early diagnosis of cancer.