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

• Periodically ordered macroporous BiVO 4 photoanode is designed for ultrasensitive immunosensing. • Au nanoparticles with local surface plasmon effect improve biosensing performance. • The immunosensor shows a sensitive response to 50 fg-150 ng mL -1 A β . • The immunosensor demonstrates recovery rates of 99.3%-100.6% for A β detection in real human serum. 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 (BiVO 4 )-based photoelectrochemical immunosensor is constructed for the ultrasensitive detection of amyloid- β (A β ) peptides. The sensing probe is composed of plasmonic Au nanoparticles (NPs) on the surface of 3DOM BiVO 4 with the A β -specific antibody. Attributing to the nanoplasmonic effect and the periodic ordered porous structure, the Au NPs/3DOM BiVO 4 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 A β -specific antibody immobilized on the surface of Au NPs/3DOM BiVO 4 selectively coordinates with the A β peptide, resulting in an ultrasensitive detection for A β 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. A novel PEC sensing probe of 3DOM BiVO 4 loaded with plasmonic Au NPs is designed for sensitive and selective detection of A β peptide. Attributing to the plasmon effect and periodic ordered porous structure, the Au NPs/3DOM BiVO 4 photoelectrode shows a significant photocurrent response resulting from the strong light scattering effect and the enhanced separation of photoinduced charge carriers, thus contributing to a promising sensing performance with a wide linear relationship range and a low limit of detection.