A photoelectrochemical sensor for highly sensitive detection of amyloid beta based on sensitization of Mn:CdSe to...

A high sensitivity photoelectrochemical (PEC) immunosensor for amyloid beta (Aβ) detection, which has great neurotoxic effect on the progression of Alzheimer's disease (AD), was presented based on the sensitization of Mn²⁺ doped CdSe (Mn:CdSe) to Bi₂WO₆/CdS electrode. Bi₂WO₆ was synthesized successfully with a unique flower-like amorphous structure, providing a merit to load functional CdS for obtaining an expected PEC response. Mn:CdSe was used to label Aβ for acquiring Mn:CdSe-Aβ bioconjugate and enhancing the detection sensitivity via the competitive immunoreaction of Mn:CdSe-Aβ and Aβ with antibody immobilized on Bi₂WO₆/CdS electrode. The doped of Mn²⁺ in CdSe nanoparticles could induce energy defect that impeded the recombination of photo-generated charges, and greatly enhanced PEC response for ultrasensitive detection of Aβ. The proposed immunosensor for Aβ showed a linear range of 0.2 pg mL^-1-50 ng mL^-1 with a detection limit of 0.068 pg mL^-1, also with good stability, high selectivity, and acceptable reproducibility. The sensitization of Mn:CdSe provided a new way for preparation of highly sensitive protein biosensors.