Photoelectrochemical immunosensing of amyloid-β peptide using nanoplasmonic macroporous bismuth vanadate for Alzheimer's disease diagnosis

Effective monitoring of biomarkers in human serum is essential for early diagnosis of Alzheimer's disease, but it is nontrivial due to the complex environment and ultralow content. Herein, a three-dimensionally ordered macroporous (3DOM) bismuth vanadate (BiVO₄)-based photoelectrochemical immunosensor is constructed for the ultrasensitive detection of amyloid-β (Aβ) peptides. The sensing probe is composed of plasmonic Au nanoparticles (NPs) on the surface of 3DOM BiVO₄ with the Aβ-specific antibody. Attributing to the nanoplasmonic effect and the periodic ordered porous structure, the Au NPs/3DOM BiVO₄ photoelectrode shows a significant photocurrent response resulting from the strong light scattering effect and the enhanced separation of photoinduced charge carriers under simulated sunlight irradiation (AM 1.5G, 100 mW cm^-2). The Aβ-specific antibody immobilized on the surface of Au NPs/3DOM BiVO₄ selectively coordinates with the Aβ peptide, resulting in an ultrasensitive detection for Aβ with a linear relationship range of 50 fg-150 ng mL^-1 and a detection limit of 25 fg mL^-1 (S/N=3). This work paves the way for constructing highly ordered macroporous photoelectrodes with functional recognition nodes to detect biomarkers for early diagnosis of neurological disorders.