Highly sensitive photoelectrochemical biosensor based on Au nanoparticles sensitized zinc selenide quantum dots for DNA detection

Herein, a sensitive photoelectrochemical (PEC) biosensor was developed for detection of target DNA based on ZnSe quantum dots (QDs)/Au nanoparticles (NPs) sensitized structure as signal tag and hybrid chain reaction (HCR) as signal amplifier. Initially, the single-stranded target DNA triggered HCR to form a long double-stranded DNA HCR product containing a great number of biotin and AuNPs. Subsequently, the product could be connected with ZnSe QDs modified by avidin through the interaction between avidin and biotin to form AuNPs/ZnSe QDs sensitized structure, in which the photocurrent signal of ZnSe QDs would be significantly enhanced under light irradiation as a result of the surface plasmon resonance of AuNPs. Impressively, the photocurrent intensity obtained by 4 nm AuNPs/ZnSe QDs was about sixfold higher than that of ZnSe QDs alone. As a application in bioassay, the constructed PEC biosensor could detect target DNA in the linear range from 1 fM to 10 nM with a detection limit of 0.33 fM. This strategy opens a new way to construct sensitive PEC biosensor for the detection of biomolecules in the bioanalysis and disease diagnosis.