A rapid, specific, and simple-to-use biosensor for amplification-free determination of microRNA based on electrical potential-assisted and ternary hybridization.

An ultra-fast, easy-to-use and non-amplification electrochemical detection platform was constructed for microRNA (miRNA) detection. A set of label-free hairpin probes and capture probes were introduced to form a ternary complex, which could enhance the selectivity and stability of miRNA detection due to the ability of reducing non-specific bind with non-target and enhancing accessibility of target to probes. Moreover, the capture probe immobilization and hybridization process were accelerated by the external electric field, shortening the detection time from 2 h to 5 min. The platform showed a detection limit of 1.28 fM under ideal experimental control conditions and had ability to identify 1- or 2-nucleotide (nt) difference. In addition, the designed sensor achieved the sensitive determination of miRNA-21 in serum samples. The excellent anti-interference capability of this detection method indicated its potential for clinical application. Its simplicity and high specificity made this method a promising tool for detecting different miRNA to assist the diagnosis of diverse cancers.