Electrochemical detection of β-amyloid peptides on electrode covered with N-terminus-specific antibody based on electrocatalytic O2 reduction by Aβ(1-16)-heme-modified gold nanoparticles

beta-Amyloid (A beta) peptides are believed to be important for the diagnosis and prognosis of Alzheimer's disease (AD) serving as reliable molecular biomarkers. In this work, we reported a simple and sensitive electrochemical strategy for the detection of total A beta peptides using gold nanoparticles modified with A beta (1-16)-heme (denoted as A beta(1-16)-heme-AuNPs). Monoclonal antibody (mAb) specific to the common N-terminus of A beta was immobilized onto gold electrode for the capture of A beta(1-16)-heme-AuNPs. The anchored A beta(1-16)-heme-AuNPs showed strong electrocatalytic O-2 reduction. Pre-incubation of the mAb-covered electrode with native A beta decreased the amount of A beta(1-16)-heme-AuNPs immobilized onto the electrode, resulting in the decrease of the reduction current of O-2 to H2O2. The competitive assay is sensitive and selective to A beta peptides. The voltammetric responses were found to be proportional to the concentrations of A beta ranging from 0.02 to 1.50 nM, and a detection limit of 10 pM was achieved. To demonstrate the viability of the method for the analysis of A beta in real sample, artificial cerebrospinal fluid (aCSF) containing A beta(1-40), A beta(1-42) and A beta(1-16) was tested. We believe that the method would offer a useful means for quantifying A beta in a biological matrix, and be valuable in the design of new types of electrochemical biosensors for the detection of peptides and proteins. (C) 2013 Elsevier B.V. All rights reserved.