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 %.