Supersandwich Nanowire/Quantum Dots Sensitization Structure-Based Photoelectrochemical "Signal-On" Platform for Ultrasensitive Detection of Thrombin.

A new photoelectrochemical (PEC) "signal-on" sensing platform based on photoactive material Bi2O3-ZnO and CdS quantum dots (QDs) sensitizer was fabricated for ultrasensitive determination of thrombin by constructing supersandwich nanowires. The CdS/ZnO/Bi2O3 sensitization structure with excellent energy level arrangement remarkably improved photoelectric conversion efficiency because of the efficient separation of the electron-hole. Moreover, the DNA supersandwich nanowire is ingeniously synthesized in one step by simple dislocation hybridization, which could carry a large amount of sensitized material CdS QDs. More importantly, with Exonuclease III (Exo III)-assisted multiple amplification, the proposed "signal-on" platform demonstrated a detection range of 10 fM to 1 μM with the detection limit of 1.41 fM for thrombin. Impressively, the PEC platform can successfully detect human serum samples with good accuracy. Above all, the CdS/ZnO/Bi2O3 sensitization photoelectric biosensing platform by using DNA nanowire in combination with Exo III-multiple amplification opens new sensitized amplification paths for supersensitive biosensing and bioanalysis.