A strand displacement signal amplification‐assisted fluorescence assay for sensitive detection of microRNA

Abstract

MicroRNA is a vital biomarker because of its abnormal expression in the emergence and development of diseases, especially in cancers. Herein, a label‐free fluorescent sensing platform is proposed for detecting microRNA‐21, coupled with the cascade toehold‐mediated strand displacement reaction and magnetic beads. Target microRNA‐21 acts as an initiator to trigger the cascade toehold‐mediated strand displacement reaction and it outputs double‐stranded DNA. After magnetic separation, the double‐stranded DNA is intercalated by SYBR Green I, resulting in an amplified fluorescent signal. Under the optimal conditions, a wide linear range (0.5–60 nmol/L) and low limits of detection (0.19 nmol/L) are exhibited. What's more, the biosensor shows great specificity and reliability between microRNA‐21 and other microRNAs involved in cancer (microRNA‐34a, microRNA‐155, microRNA‐10b, and let‐7a). Owing to the properties of fabulous sensitivity, high selectivity, and simplicity of operator, the proposed method paves a promising way for microRNA‐21 detection in cancer diagnosis and biological research.