Development of Impedimetric Immunosensor for The Detection of Amyloid Beta (1-40) on maβa/ortho-Polyphenylenediamine Modified Platinum Micro Disk Electrode

The development of an electrochemical detection of amyloid beta (A beta) (1-40) peptides as a bio marker of Alzheimer's disease (AD) was carried out on a Pt disk microelectrode. The electrode was modified with poly-ortho-Phenylenediamine (PPD) and mouse monoclonal beta amyloid antibody (mA beta A) was immobilized to form Pt/PPD/mA beta A immunosensor. The measurements were done in Phosphate Buffer Solution (PBS) by applying Electrochemical Impedance Spectroscopy (EIS) technique. The detection is evaluated by the changes in the Nyquist spectra and values of charge transfer resistance (Rct) that were extracted from a modified Randles equivalent circuit. A semi-circle Nyquist plot was observed in the presence of A beta (1-40) whereas a linear spectra were exhibited in the absence of A beta (1-40). In addition, as the concentrations of A beta (1-40) solution increased, the diameter of Nyquist plots was also increased. Surface morphology of A beta (1-40) adsorbed on microelectrode was observed using Field-emission Scanning Electron Microscope (FESEM) and Optical Microscopic. Based on these findings, a promising in vivo immunosensor for A beta (1-40) detection that can be used as an alternative in monitoring inhibitors of A beta (1-40) aggregation research.