Nuclease-propelled target dual-recycling amplification strategy integrated with cascaded sensitization effect of ZnO/CuInS2/Ag2Se photoactive structures for lab-on-paper photoelectrochemical microRNA bioassay

Herein, a new paper-based photoelectrochemical (PEC) biosensor was proposed for microRNA determination based on the cascaded sensitization effect of ZnO/CuInS2/Ag2Se photoactive structures and nuclease-propelled target dual-recycling amplification strategy. Concretely, the paper-based ZnO sensitized with CuInS2 were served as a signal generator and a substrate for immobilizing hairpin DNA (H2). Ag2Se quantum dots (QDs), labeling at the terminal of probe DNA (pDNA), served as the sensitization agents. When target microRNA existed, duplex-specific nuclease activated the first recycling amplification procedure, resulting in the release of numerous converted DNA sequences (cDNA). Afterward, the second target recycling amplification procedure was initiated upon the H2-immobilized electrode was incubated with cDNA and lambda exonuclease, which made massive short DNA fragments free from H2. Consequently, a small quantity of target miRNA-141 was converted into abundant short DNA fragments, which could further hybridize with Ag2Se QDs labelled pDNA, activating the cascaded sensitization effect of ZnO/CuInS2/Ag2Se photoactive structures and giving great signal enhancement. Benefiting from the considerable signal amplification enabled by nuclease-assisted target dual-recycling amplification strategy and cascaded photosensitive structures, the proposed biosensor realized the ultrasensitive detection of miRNA-141 with great accuracy and selectivity, which rendered a prospective paradigm to develop high-performance microfluidic paper analytical devices.

Automated summary

In this study, a new paper-based photoelectrochemical biosensor was developed for microRNA determination using the cascaded sensitization effect of ZnO/CuInS2/Ag2Se photoactive structures and a nuclease-propelled target dual-recycling amplification strategy. The biosensor achieved ultrasensitive detection of miRNA-141 with high accuracy and selectivity, demonstrating great potential for developing high-performance microfluidic paper analytical devices.