Polymeric bilayer modified microelectrodes for in-vivo determination of neurotransmitter dopamine

A-composite polymer carbon fiber electrode modified with Nafion and cellulo se acetate is described. The modified electrode discriminates against both anionic reactants and big molecular organic compounds. The bilayer configur ation is prepared in two steps. First, the carbon fiber electrode is coated with Nafion, then followed by air evaporation of the solvent, the electrod e is dipped in a cellulose acetate solution and hydrolyzed for a selected t ime. The permeability of the film is explored by use of rotating disk elect rode measurements. Parameters affecting the film electrochemistry are inves tigated. The resulting electrodes show high selectivity and stability in bo dy fluids. For in-vivo voltammetry, the composite polymer modified electrod e has been used for detection of the oxidative current of neurotransmitter dopamine in rat brain, while it inhabits the oxidation of anionic neurotran smitter metabolites and some electroactive compounds.