Cascaded Nanosensors for Ultrasensitive Detection of miRNA in Cancer Cells

MicroRNA (miRNA) detection is of considerable significance in the diagnosis and treatment of cancer. The expression level of cancer-related miRNA differs significantly in various cancer cell types, and it remains challenging to detect miRNA at both high and low levels accurately using a conventional sensor with fixed limit of detection and narrow linear detecting range. Herein, three kinds of gold nanoparticle-quantum dots composite were constructed by reasonable DNA sequence design. By stacking these nanocomposites sequentially , three kinds of sensors of single , double and multiple amplifications based on entropy-driven catalytic circuits were successfully established. The product of the upper nanocomposite was served as the catalyst of the downstream nanocomposite to activate disassembly, inducing high-order amplification. With stacking a nucleic acid circuit of the sensor, the detection limit of the sensor was reduced by one order of magnitude. Finally, the nanosensor had a detection limit of fmol/L. By stacking entropy-driving nucleic acid circuits , a novel , dynamically tunable nanosensor was established for quantitatively detecting miRNA with different expression levels in cancer cells.