Electrochemical detection of β-amyloid peptides on electrode covered with N-terminus-specific antibody based on electrocatalytic O_2 reduction by Aβ(1-16)-heme-modified gold nanoparticles

摘要

β-Amyloid (Aβ) 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 Aβ peptides using gold nanoparticles modified with Aβ(1-16)-heme (denoted as Aβ(1-16)-heme-AuNPs). Monoclonal antibody (mAb) specific to the common N-terminus of Aβ was immobilized onto gold electrode for the capture of Aβ(1-16)-heme-AuNPs. The anchored Aβ(1-16)-heme-AuNPs showed strong electrocatalytic O_2 reduction. Pre-incubation of the mAb-covered electrode with native Aβ decreased the amount of Aβ(1-16)-heme-AuNPs immobilized onto the electrode, resulting in the decrease of the reduction current of O_2 to H_2O_2. The competitive assay is sensitive and selective to Aβ peptides. The voltammetric responses were found to be proportional to the concentrations of Aβ ranging from 0.02 to 1.50nM, and a detection limit of 10pM was achieved. To demonstrate the viability of the method for the analysis of Aβ in real sample, artificial cerebrospinal fluid (aCSF) containing Aβ(1-40), Aβ(1-42) and Aβ(1-16) was tested. We believe that the method would offer a useful means for quantifying Aβ in a biological matrix, and be valuable in the design of new types of electrochemical biosensors for the detection of peptides and proteins.