Capturing and Detection of Amyloid-Β Aggregation with Affinity Peptide-Incorporated AU Electrode

In solution, the Aβ peptides fold into α-helical or random extended chain structures, as well as soluble β-sheet structure that eventually precipitate as amyloid and the complicated aggregation mechanism study needed new detection techniques. In this study, we demonstrate a novel affinity peptide-incorporated (with amino acid sequence of GNNPLHVHHDKRGGGC) Au electrochemical biosensor for the detection of tyrosine residues on Aβ monomers. Cyclic Voltammetry (CV) and Atomic Force Microscopy (AFM) were used to validate biosensor assembly and functionality. CV was employed for biosensor interrogation in the presence of Aβ oligomers or monomers. The attachment of Aβ peptides to Au was confirmed by CV and AFM imaging. The intrinsic oxidation signal of the captured Aβ peptides, containing a single tyrosine (Tyr) residues, was monitored at a peak potential of 0.6 V (vs Ag/AgCl within this sensor). The affinity polypeptide composite electrode was obtained by optimizing the modification process, which can respond to the concentration from 1 pM to 1 µM of Aβ 1-42 polypeptide monomer molecule. The peak current intensities were concentration dependent. And with the exposure decreasing with the Aβ aggregation, the peak current also decreased and compared with AFM images to reveal the Aβ aggregation pattern. The proposed process provides new routes for analysis of Aβ aggregation interactions and electrochemical biosensor development.