Photoelectrochemical biosensor based on CdS quantum dots anchored h-BN nanosheets and tripodal DNA walker for sensitive detection of miRNA-141.

Herein, a high-sensitivity photoelectrochemical (PEC) biosensor was developed based on CdS quantum dots (QDs) sensitized porous hexagonal boron nitride (h-BN) nanosheets (NSs) and the multiple sites tripodal DNA walker (TDW) formed by catalytic hairpin assembly (CHA). Noticeably, the porous structure of h-BN NSs gives it a lasting gift of large specific surface areas and extensive active reaction sites, which makes it possible to be employed as photoelectric substrate material. The h-BN/CdS QDs composite material promotes the transmission of photogenerated electrons and holes, the outstanding photoelectric conversion efficiency. Meanwhile, the CHA-formed TDWs triggered by miRNA-141 moved on track strand-functionalized electrode, so that a large number of alkaline phosphatase (ALP) was immobilized on the electrode surface and further in situ catalyzed ascorbic acid 2-phosphate (AAP) to produce ascorbic acid (AA) as the electron donor. As the result of the decisive influence of electron donor on PEC biosensor, the sensitive detection of miRNA-141 was realized. The proposed PEC biosensor displayed an excellent linear relationship ranging from 1 fM to 100 nM with a detection limit of 0.73 fM, providing a powerful strategy for early clinical diagnosis and biomedical research.