Electrochemistry and electrocatalysis with myoglobin in biomembrane-like DHP-PDDA polyelectrolyte-surfactant complex films

The polyelectrolyte-surfactant complex DHP-PDDA was prepared by reacting th e anionic surfactant dihexadecylphosphate (DHP) with polycationic poly(dial lyldimethylammonium) (PDDA). Thin films made from DHP-PDDA on solid substra tes demonstrated an ordered multibilayer structure by XRD and DSC. Incorpor ated myoglobin (Mb) in DHP-PDDA films on pyrolytic graphite (PG) electrodes showed a pair of well-defined and nearly reversible cyclic voltammetric pe aks for the Mb Fe(III)/Fe(II) couple at about -0.3 V vs SCE in pH 7.0 buffe rs. Electron transfer between Mb and PG electrodes was greatly facilitated in the film microenvironment. The positions of the Soret absorption band su ggest that Mb maintains its secondary structure similar to its native state in DHP-PDDA films in the medium pH range. Mb could act as an enzyme-like c atalyst in DHP-PDDA films as demonstrated by catalytic reduction of trichlo roacetic acid, nitrite, and oxygen with a decrease in the electrode potenti als required. Mb-DHP-PDDA films may thus have potential application as bios ensors. (C) 2001 Academic Press.