Electrochemical impedance spectroscopy analysis of A-beta (1-42) peptide using a nanostructured biochip

A-beta (1-42) peptide (Aβ (1-42)) is a potential candidate for the prediction of Alzheimer's disease. In this study, we demonstrate a nanostructured biosensor based on electrochemical impedance spectroscopy (EIS) with uniformly deposited gold nanoparticles (GNPs) as the sensing electrode for effective detection of Aβ (1-42). An anodic aluminum oxide (AAO) layer with a nanohemisphere array was used as the substrate. A gold thin film was sputtered onto the AAO substrate to serve as the electrode for GNP deposition and the sensor for Aβ (1-42). Aβ (1-42) antibody was prepared, and its specificity with Aβ (1-42) was verified by Western blot. We observed aggregation of Aβ (1-42) at 1 μg ml−1. The morphology of Aβ (1-42) was in the form of round aggregates with diameter of around 1500–2000 nm. EIS measurements for nanostructured biosensors were used to determine the concentration of Aβ (1-42). The plot for the dependence of EIS concentration measurement resulted in an equationΔRct = 29098*log [Aβ (1-42)] + 90150 with an R2 value of 0.9916. The linear detection range was between 1 pg ml−1 and 10 ng ml−1 of Aβ (1-42).