Cascaded Nanosensors For Imaging-based Quantification Of MiRNA In The Cancer Cells

MicroRNA(miRNA)detection is of considerable significance both in disease diagnosis and in the study of miRNA function.The importance of miRNA is due to the complicated regulatory functions it plays in various life processes and its close relationship with some diseases.However,the characteristics of miRNAs,such as high sequence homology among family members,short lengths and low abundance in real samples,have made the specific and sensitive detection become more challenging.With the rise of nanotechnology,nucleic acid circuits have been widely applied in biosensing and bioimaging as an effective signal amplification strategy in recent years.The expression level of miRNA in different cells is high or low.A single nucleic acid circuit sensor can not simultaneously quantitatively detect miRNA with different expression levels.In this paper,DNA-modified gold nanoparticles and DNA-functionalized quantum dots are assembled into three groups of nanocomposites.By stacking these nanocomposites,three kinds of nanosensors,single nucleic acid circuit amplification,double nucleic acid circuit amplification and triple nucleic acid circuit amplification are constructed.With adding a nucleic acid circuit of the sensor,the detection limit of the sensor can be reduced by one order of magnitude.Finally,the triple nucleic acid circuit amplification nanosensor has a detection limit of fM and can detect lower concentrations of miRNA.This type of sensor has high sensitivity and good specificity.We can directly calculate the concentrations of miRNA in different cells by the recovery rate of fluorescence intensity and realize quantitative detection of miRNA.By stacking entropy-driving nucleic acid circuit,we have developed a novel,dynamically tunable nanosensor that is capable of quantitatively detecting miRNA of different expression levels in cancer cells.