Amplified fluorescence sensing of miRNA by combination of graphene oxide with duplex-specific nuclease
A novel fluorescent sensing platform for miRNA detection is developed in this work, which simply combines the fluorescence quenching efficiency of graphene oxide (GO) and the duplex-specific nuclease (DSN)-induced target recycling. Fluorophore-labeled DNA strands acting as probes were physically adsorbed onto the GO surface, leading to fluorescence quenching. In the presence of target miRNA, the DSN cleaved the probe DNA in the DNA–RNA hybrid duplex into small fragments and the miRNA was released from the duplex. Thus the recycling of the target miRNA was realized, producing numerous small DNA fragments. After the introduction of GO into the sensing solution, a strong fluorescence emission was observed due to the weak interaction between the short DNA fragments and GO. With this approach, a sub-picomolar detection limit of miRNA could be achieved within 40 min. What is more, this biosensor exhibited good sequence selectivity due to the great sequence discrimination ability of DSN. The proposed sensor is sensitive, specific, simple and rapid, paving a way to the miRNA analysis.