Amperometric biosensor for microRNA based on the use of tetrahedral DNA nanostructure probes and guanine nanowire amplification

MicroRNAs are endogenous noncoding RNAs that play critical roles in biological processes and can be considered as molecular markers for early diagnosis and pathogenesis of diseases. The authors describe a highly sensitive electrochemical biosensor for microRNA that is based on the use of tetrahedral DNA nanostructure probes and guanine nanowire amplification. The DNA tetrahedral probe is self-assembled on a gold electrode and enhances reactivity, accessibility, and molecular recognition efficiency. Combined with the tetrahedral probe, the guanine nanowire amplifies the signal and improves the analytical performance of the biosensor. Operated best at a voltage of typically 150 mV (vs. Ag/AgCl), the sensor has a linear response to the logarithmic microRNA concentration in the 500 f. to 10 nM range, with a 176 f. detection limit. It is highly selective and can be applied to real samples. It is concluded that this strategy has a good potential with respect to the determination of microRNA in clinical diagnosis and in biological research.