Pulse counting of nanobubbles inside DNA-functionalized nanopores and the application for highly sensitive...

In conventional electrochemical biosensors, nanobubbles generated by electrochemical reactions typically adhere to the electrode interface, which affect the accuracy of measurements. In this study, we take good use of nanobubbles as the signal source and effectively address this limitation. An ultrasensitive approach for the detection of miRNA is further developed coupling catalytic hairpin assembly and DNA-functionalized nanopores to generate nanobubbles. DNA probe H1 is first immobilized inside 3-aminopropyltriethoxysilane (APTES)-modified nanopores through amide reaction. The poly(G) segment at the terminus of H1 transforms to G-quadruplex (G4) when the hairpin structure is opened by target miRNA. After capturing hemin, the generation of oxygen nanobubbles is catalyzed. DNA probe H2 is further introduced, and catalytic hairpin assembly occurs, facilitating target recycling. The concentration of miRNA is found to be positively correlated with the pulse counts of nanobubbles per unit time. This electrochemical method for miRNA detection shows significant promise in the field of disease diagnostics and provides exciting opportunities for the development of novel nanobubble-based biosensors.