VOLTAMMETRIC DETECTION OF NO IN THE RAT-BRAIN WITH AN ELECTRONIC CONDUCTING POLYMER AND NAFION(R) BILAYER-COATED CARBON-FIBER ELECTRODE

An NO sensor based on a carbon fibre microelectrode modified by a poly (N-methylpyrrole) incorporating [(H2O)(FePW11O39)-P-III](4-) sublayer and coated by a Nafion(R) external layer is described. It is based on the NO oxidation current measured by differential normal pulse voltamm etry. In solution, a linear response is obtained between this oxidatio n current and the NO concentration in the range 10(-7) to 10(-3) M wit h a sensitivity of 2.65 +/- 0.15 nA mu M-1. A comparative study has be en carried out with poly(N-methylpyrrole) doped with ClO4-, polypyrrol e doped with sulfonated nickel porphyrin, polypyrrole and poly(N-methy lpyrrole) doped with Nafion(R). This sensor implanted in the rat brain is efficient to detect in real time the NO released, The validation o f in vivo measurements is made by injecting the rat with an NO-synthas e inhibitor. (C) 1997 Elsevier Science S.A.