Capacitor-parallel-amplified decoupled photoelectrochemical/electrochromic dual-mode bioassay for sensitive detection of microRNA with high reliability.

To achieve sensitive detection of low-content microRNA, photoelectrochemical/electrochromic dual-mode sensor with intrinsically low background signal has been developed, but the two detection modules are usually designed with a series-connected structure, which may cause signal interference and thus affect the detection reliability. To solve the above problems, a decoupled dual-mode bioassay for sensitive miRNA-21 detection with high reliability is constructed in this work, by selecting two capacitors to realize parallel amplification for the two detection modules, supplemented with a 3D DNA nanoring photoelectrode signal amplification strategy. The complete decoupling of the two detection modes, photoelectrochemical and electrochromic, as well as the use of digital multimeter, improves the reliability and accuracy of the sensor, and also frees it from dependence on electrochemical workstation, making detection more intuitive and faster. With simple structure, low cost, good reproducibility, high sensitivity, and easy operation, the capacitor-parallel-amplified decoupled photoelectrochemical/electrochromic dual-mode bioassay has broad application prospect in on-site point-of-care detection of diseases and low-cost clinical diagnosis. The design idea of decoupled dual-mode detector can also be extended to the construction of other dual-mode methods.