Quantitative Analysis Of MicroRNA Content By Fluorescence Imaging In Cancer Cells Using Dual-color Fluorescence Nanosensor

Cancer is one of the most fatal diseases in the 21st century.It is generally developed from malignant tumors and has the characteristics of metastasis,uncontrollability and abnormal proliferation.At present,cancer is widely concerned in medicine.The clinical detection methods of cancer generally include tumor marker detection,gene detection,molecular imaging technology and pathological examination.Early detection of cancer is of significance to prevent tumor deterioration and increase the number of cures.MiRNAs are a class of RNA with 18-25 nucleotide sequences,which plays a key role in gene expression and is closely related to the development,differentiation,proliferation,apoptosis and disease progress of organisms.The abnormal expression of miRNA is related to tumor types.Therefore,it is usually used as a biomarker of tumor and plays a predictive and diagnostic role in the early screening of cancer.In this paper,a real-time photo-controlled nanosensor is designed,which can be applied to tumor cell imaging and quantitative detection of miRNA.The biosensor is constructed by self-assembly and self-assembly of DNA containing photosensitive group PC-linker through DNA modified by two fluorescent dyes,which are DNA functional gold nanoparticles and emission wavelength separation.302 nm UV light as the starting switch of the system and when UV light applied to the system,the photosensitive group is opened and a fluorescent dye is released.Then,the miRNA in cancer cells is detected by two-step entropy driven site-mediated continuous displacement reaction.One of the fluorescence signal intensity is used as internal reference signal to calibrate the content of the assembly entering the cell;the other fluorescence signal of the fluorescent dye is recovered and used as the detection signal.Through the detection of two fluorescence signal intensities and the calculation of their ratio,the quantitative analysis of miRNA content in cells can be achieved.The system can deduct the background signal error caused by the different content of the assembly in the cell,which can improve the detection accuracy significantly,and reduce the detection limit and realize the quantitative calculation of miRNA due to the design of catalytic cycle system.