Detection of microRNA-21 based on smartly designed ratiometric electrochemical sensor and dual-signal amplification

MicroRNA (miRNA) serves as an effective and viable biomarker for early diagnosis and monitoring of cancer disorders. It is highly expressed in tumor cells, including lung cancer, liver cancer and lymphoma. Herein, we propose a ratiometric electrochemical sensor for ultrasensitive detection of miRNA-21 using dual signal amplification, hybridization chain reaction and Exo III assisted-amplification. Methylene blue (MB) and Hemin are chosen as two electrochemical species. Then the ratiometric electrochemical sensor were developed, which showed favorable performance of miRNA-21 detection, and exhibited a detection concentration range from 1 fM to 10 nM. Notably, the limit of detection for this biosensor was 0.15 fM. Overall, this strategy for miRNA detection holds significant promise for early cancer screening.