A novel recyclable surface-enhanced Raman spectroscopy platform with duplex-specific nuclease signal amplification for ultrasensitive analysis of microRNA 155

In this work, a recyclable surface-enhanced Raman spectroscopy (SERS) biosensor was fabricated for ultrasensitive detection of miRNA 155 by using magnetic substrate (Fe3O4@PDA/Pt) and duplex-specific nuclease signal amplification (DSNSA) strategy. Here, the Fe3O4@PDA/Pt was used as SERS platform to immobilize toluidine blue Raman reporter and capturing DNA (S1), in which polydopamine (PDA) could avoid the aggregation of Fe3O4 and enhance the biocompatible of platform. When Au nanoflowers (AuNFs) modified probe DNA (S2) was partly hybridized with S1, an initial strong Raman signal (“on” status) was obtained by the approaching between AuNFs and TB. In the presence of target microRNA 155, they could completely hybridize with S2, which led to the isolation of S2 from substrate. Under the assistance of DSN enzyme, the S2 in the DNA/RNA duplex was hydrolyzed to release target miRNA 155, which could trigger another cycle. Thus the AuNFs were departed from TB with an obviously decreased signal. More important, with the application of AuNFs-modified S2, the Raman reporter was continuously assembled on the substrate throughout the detection. After the adding of S2, the S1 could re-hybridize with S2, which led the SERS biosensor return to “on” status, therefore the regeneration of biosensor was easily realized. From this principle, the recyclable biosensor could achieve a wide linear range from 1 fM to 10 μM and the detection limit was 0.28 fM. Herein, we proposed a novel method to construct the ultrasensitive and recyclable SERS platform, which was expected to be used in the clinical applications.