Impedance Studies of Surfactant-Polyion-Cholesterol Films

Abstract

Studies of the temperature dependence of electrical impedance showed that molecular organization of films of dioctadecyldimethylammonium bromide (DODAB) and sodium poly(styrenesulfonate) (PSS) or the ionomer Nafion on pyrolytic graphite electrodes was improved by annealing in water. Films prepared by dipping Nafion‐coated electrodes into DODAB dispersions had similar phase transition temperatures to water‐annealed cast DODAB‐Nafion films. The work also demonstrated the influence of cholesterol content on the impedance and phase transition properties of the films. Impedance changes upon binding of bovine serum albumin (BSA) to anti‐BSA in DODAB‐Nafion films suggest that preparation methods and optimized amount of cholesterol are important for applications of impedance‐based detection of macromolecular binding events using these film materials.