Electrochemical impedance spectroscopy for study of amyloid β-peptide interactions with (-) nicotine ditartrate and (-) cotinine

Immobilization of amyloid beta (A beta) (1-40) peptide on Au-colloid modified gold electrodes has been studied. Colloidal Au was self-assembled onto gold electrodes through the thiol groups of 1,6-hexanedithiol monolayer. Next, buffered aqueous solution of A beta (1-40) peptide existing in the beta-sheet structure in the acidic media was dropped on the electrode surface. Each step of electrode modification has been confirmed with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The changes of the resistance of the layer with deposited A beta (1-40) peptide, occurred under stimulation by different concentration of (-) nicotine ditartrate and (-) cotinine were measured with EIS and were used for the calculation of association constants. The gentle measuring conditions applied in electrochemical impedance spectroscopy, together with suitable environment for biomolecules immobilization created by Au-colloid, might be recommended as the analytical tool for assessing the effectiveness of potential drugs used in Alzheimer's disease (AD) therapy. (c) 2006 Elsevier B.V. All rights reserved.