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

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