An electrochemical peptide-based biosensor for the Alzheimer biomarker amyloid-β(1-42) using a microporous gold nanostructure

Alzheimer's disease (AD) is connected to aggregation of amyloid-beta (A beta) peptide and formation of insoluble plaques in the brain. A beta level can be monitored as an AD early diagnosis route. In this study, an irregular shaped microporous gold nanostructure with a typical size of 150x250 nm was electrodeposited on a polycrystalline gold surface at 0 mV (vs. AgCl) using sodium alendronate. The nanostructure was then characterized by field-emission scanning electron microscopy. An electrochemical peptide-based biosensor was fabricated by immobilizing an A beta((1-42))-binding peptide on the gold nanostructure. Binding of A beta((1-42)) by the peptide was followed electrochemically using ferro/ferricyanide as a redox probe. Differential pulse voltammograms in a potential range of 0-500 mV (vs. AgCl) with typical peak potentials at 224 mV are linear in the 3-7000 pg mL(-1) A beta((1-42)) concentration range, with a 0.2 pg mL(-1) detection limit. The biosensor is free of interferences and was applied to the quantitation of A beta((1-42)) in artificial cerebrospinal fluid and spiked serum samples.