A-beta (1-42) peptide (A beta (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 A beta (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 A beta (1-42). A beta (1-42) antibody was prepared, and its specificity with A beta (1-42) was verified by Western blot. We observed aggregation of A beta (1-42) at 1 mu g ml(-1). The morphology of A beta (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 A beta (1-42). The plot for the dependence of EIS concentration measurement resulted in an equation Delta Rct=29098*log [A beta (142)] + 90150 with an R-2 value of 0.9916. The linear detection range was between 1 pg ml(-1) and 10 ng ml(-1) of A beta (1-42). (C) 2014 Elsevier Ltd. All rights reserved.