Self-assembly of DNA-hyperbranched aggregates catalyzed by a dual-targets recognition probe for miRNAs SERS detection in single cells.

MicroRNAs (miRNAs) are very important for the early diagnosis and prognosis of tumors. In this work, we achieved the simultaneous detection of microRNA-155 (miR-155) and microRNA-21 (miR-21) with a dual target recognition probe (DRP) based on the nonlinear hybridization chain reaction (HCR). The multi-branched DNA products, three-dimensional multi-hotspot DNA dendrimers (3DmhD) were used in the amplification of the target miRNAs signal. The DRP is constructed with a core of gold nanocages (AuNCs), modified by nucleic acid probes and labeled with Raman signaling molecules ROX and Cy3. Experiments demonstrated that DRP could activate the multi-branched DNA reaction and generate 3DmhD in the presence of miR-155 and miR-21, which can achieve effective amplification of miR-21 and miR-155. When Surface Enhanced Raman Scattering (SERS) analysis was performed on 3DmhD, the multi-hot spot effect of 3DmhD significantly enhanced the signals of ROX and Cy3, allowing ultra-sensitive detection of miR-21 and miR-155 in vitro. To our delight, DRP also exhibited sensitive specificity and significant signal amplification for intracellular miRNAs. These results revealed that DRP has the potential to screen tumor cells by analyzing the expression levels of intracellular miRNAs.