Versatile photoelectrochemical biosensor based on AIS/ZnS QDs sensitized-WSe nanoflowers coupled with DNA nanostructure probe for"On-Off"assays of TNF-α and MTase.

Herein, a novel multifunctional photoelectrochemical (PEC) biosensor based on AgInS (AIS)/ZnS quantum dots (QDs) sensitized-WSe nanoflowers and DNA nanostructure signal probe was designed to achieve ultra-sensitive "On-Off" detection of human tumor necrosis factor α (TNF-α) and methylase Dam MTase (MTase). AIS/ZnS QDs as an excellent photosensitive material was found to match WSe in energy level for the first time, and the photocurrent signal after sensitization was 65 times that of WSe nanoflowers and 17.9 times that of AIS/ZnS QDs. Moreover, abundant AIS/ZnS QDs were loaded on the TiO nanoparticles with good conductivity by DNA to fabricate a multifunctional probe, which can not only amplify signal but also specifically recognize target. When target TNF-α was present, the AIS/ZnS QDs signal probe was attached to the WSe nanoflowers-modified electrode through binding to aptamer, and the amplified PEC signal was generated for "on" assay of TNF-α. Furthermore, Dam MTase as second target induced methylation of hairpin H, so it is cleaved by the endonuclease DpnI, resulting in the shedding of AIS/ZnS QDs signal probe for signal "off" detection of MTase. This work opened a new photosensitized probe and developed a promising PEC biosensor for dual-targets assay. By programming the DNA nanostructure, the biosensor can detect versatile targets in a simple and sensitive method, which has good practical application value in human serum.