Here, we present a dual amplification strategy based on a duplex-specific nuclease and a hybridization chain reaction, which has been designed for the highly sensitive detection of miRNAs. In the first step, a loop amplification strategy based on a duplex-specific nuclease was employed to obtain a large number of ssDNA reporters that then act as initiators to trigger the next amplification step. The second step involves a hybridization chain reaction based on two hairpin DNAs denoted as H-1 and H-2. Doxorubicin-CdTe quantum dots, which function as detecting indicators that intercalated into the hybridization chain reaction products, lead to significantly amplified electrochemiluminescence signal readout. This dual amplification strategy enabled the sensitive detection of let-7d from 10 aM to 10 nM with a detection limit of 10 aM, and offered an excellent capacity to discriminate between microRNA family members. This assay therefore offers great potential applications in biomedical research and early clinical diagnosis. (C) 2017 Elsevier B.V. All rights reserved.