Cascaded recycling amplification mediated in situ synthesis of silver nanoclusters for the construction of sensitive and label-free electrochemical sensor

A growing number of studies have shown the crucial role of microRNA (miRNA) sensing in cancer clinical diagnosis and prognosis research. In this study, a label-free and enzyme-free electrochemical sensor was presented to achieve sensitive determination of miRNA 122, which was constructed based on in situ synthesis of silver nanoclusters (AgNCs) mediated by cascaded recycling amplification. The efficient and cascaded recycling amplification was initiated by the target miRNA 122, resulting in the release of signal probe with rich cytosine bases, which would be loaded on the sensing interface for in situ synthesis of silver nanoclusters, leading to dramatically increased current for quantitative analysis. This method achieved selective and robust miRNA 122 sensing in human serum samples with a detection limit down to 27 aM. The proposed work would provide an innovative method for determining different biomarkers, holding great potential for boosting the development of clinical diagnosis and drug investigation. •An innovative electrochemical sensor was constructed for sensitive detection of microRNA.•The synergistic amplification of the system achieved a low detection limit of 27 aM.•Real sample analysis was realized due to the excellent selectivity and anti-interference ability of the sensor.•The label-free and enzyme-free operation endowed the advantages of being convenient, robust and inexpensive.•The sensing system was promising for applications in clinical diagnosis and drug investigation.