Ultrasensitive assay of amyloid-beta oligomers using Au-vertical graphene/carbon cloth electrode based on poly(thymine)-templated copper nanoparticles as probes

Abstract Amyloid-beta (Aβ) oligomers have been become believable biomarkers for predicting and diagnosing Alzheimer’s disease (AD). Herein, an ultrasensitive electrochemical assay for detection of Aβ oligomers was built based on the Au nanoparticles-modified vertical graphene/carbon cloth (Au-VG/CC) as substrate electrode and in-situ synthesized copper nanoparticles (CuNPs) as signal probes. For the biosensor preparation, the VG/CC film was firstly treated by the electrodeposition of Au nanoparticles, and the Au-VG/CC electrode provided large surface area and high conductivity. Then the residues 95-110 of cellular prion protein (PrPC) as the specific receptor for Aβ oligomers were immobilized on the Au-VG/CC electrode surface by the Au-S bond. After the selective recognition to Aβ oligomers, the poly(thymine)-templated CuNPs as the electrochemical probes were introduced by the design of aptamers. This assay for Aβ oligomer detection showed a good performances including ultrahigh sensitivity with a low detection limit of 3.5 pM, excellent specificity, and great stability. This biosensor also presented feasibility for sensing Aβ oligomers in serum samples of AD patients, and would contribute to understand the role of Aβ oligomer as a biomarker for the early diagnosis of AD.