RESUMO
MicroRNAs (miRNAs) play an important role in multiple biological processes and can be used as biomarkers for clinical disease diagnosis, so their detection is of great importance. Here, manganese dioxide (MnO2) nanosheet acts as carrier to deliver DNAzyme probes into cells through endocytosis, where intracellular glutathione (GSH) reduces the MnO2 nanosheet to manganese ions (Mn2+) and releases the probes. The generated Mn2+ can be further used as an effective cofactor to activate the DNAzyme probe, and cleave the DNA strand into two fragments. Then, the miRNA-155 in the cells can hybridize with the cleaved fragment to cause the fluorescence signal change of the probe. The proposed proportional fluorescent method has been applied to the imaging of miRNA-155 in HeLa cells and HepG2 cells with the estimated detection limit (LOD) as 1.6 × 10-12 M. The new method can provide great help for cancer diagnosis and biological research related to miRNA.