Multiplexed detection of microRNAs by tuning DNA-scaffolded silver nanoclusters

A universal silver-nanocluster method coupled with target-triggered isothermal exponential amplification reaction (TIEAR) is developed for light-up fluorescent detection of multiple microRNAs (miRNAs) in a label-free format. Taking advantage of the interesting feature of the fine-tuned emission spectrum of fluorescent DNA-scaffolded silver nanoclusters (DNA/AgNCs), our proposed assay is designed such that the different miRNA targets are transferred to the different oligonucleotide reporters via the TIEAR, in which unimolecular DNAs designed for different targets are employed as the amplification templates, polymerases and nicking enzymes as mechanical activators and miRNA targets as the trigger. The produced oligonucleotide reporters act as templates for the synthesis of multicolor DNA/AgNC probes, which correspond to different target inputs. This proposed method has been well validated on the multiplex detection of miRNAs and DNAs, as well as in practical application.