ABSTRACT
There is high demand for a sensitive method for miRNA detection in clinical diagnosis. In this work, we developed a method for miRNA detection based on the surface plasmon-enhanced energy transfer ( SPEET ) between gold nanoparticles ( AuNPs ) and silver nanoclusters ( AgNCs ) , coupled with DNA polymerase and nicking enzyme-assisted isothermal amplification for target recycling. Two DNA probes ( Probe a and Probe b) were assembled onto the surface of AuNPs to form Probe b-Probe a-AuNP conjugates. Probe a consisted three domains:the complementary sequence of miRNA, the specific site of the nicking enzyme, and the self-assembly sequence for AgNCs. The 3′ end of Probe a was modified with thiol as a binding site for AuNPs. The SPEET of AgNCs and AuNPs was inhibited when miRNA was added to produce the dumbbell shaped template by polymerase. The template could promote synthesis of AgNCs, resulting in replacement and subsequently recycling of the target molecule for signal amplification. In comparison with the traditional method of miRNA detection with commercial RT-PCR kits, this method avoided the process of reverse transcription and was easy to perform. In addition, this method with a detection limit of 2. 5×10-11 mol/L was cost-effective, label-free, and highly selective for detecting miRNA, and could be applied to the analysis of miRNA in biological samples.