Electrochemical Immunosensor for the Sensitive Detection of Alzheimer's Biomarker Amyloid-β (1–42) Using the Heme-amyloid-β (1–42) Complex as the Signal Source

The amyloid-β peptide (1–42) (Aβ 42 ) can provide high diagnostic accuracy for the early diagnosis of Alzheimer's disease (AD). In this study, an immunosensor based on the peroxidase-like activity of heme-Aβ 42 was designed for Aβ 42 detection. The glassy carbon electrode (GCE) was electrodeposited Au particles (GCE/Au). The GCE/Au was modified using polythionine-methylene blue (PTH−MB), AuNPs, monoclonal antibody (anti-Aβ 42 ), and bovine serum albumin (BSA), successively. The GCE/Au/PTH−MB/AuNPs/anti-Aβ 42 /BSA could competitively recognize Aβ 42 and heme-Aβ 42 . The anchored heme-Aβ 42 showed strong electrocatalytic activity between H 2 O 2 and ferrocenemethanol. Under optimum conditions, we determined detection limits of 17.3 pM in PBS pH 7, 25.2 pM in serum, and 23.8 pM in saliva. The recovery ranged from 71.0 % to 117.8 %.