Electrochemical microsensor for in vivo measurements of oxygen based on Nafion and methylviologen modified carbon fiber microelectrode

An electrochemical microsensor based on carbon fiber microelectrode (CFME) chemically modified with the perfluorinated cation-exchange polymer, Nafion and methylviologen (MV) and its application for in vivo voltammetric measu rements of oxygen (O-2) are described. The microsensor shows a high catalyt ic activity for the reduction of O-2 With a good reproducibility, high sens itivity and selectivity and significant ability against electrode fouling. The current is linear with the concentration of O-2 in a range from 9.0 x 1 0(-6) to 2.0 x 10(-4) mol/L with a calculated detection limit, at a signal- to-noise ratio of 3 to 1, of 5.0 x 10(-6) mol/L and correlation coefficient of 0.9985. The relative standard deviation for 2.0 x 10-4 mol/L O-2 is 1.7 % (n = 12). Some compounds common to biological fluids such as glucose, as corbic acid, uric acid catecholamine, glutamate, glutathione, Mg2+, Ca2+, N a+, K+ and Cl- are tested in vitro and show no interferences with the volta mmetric responses to O-2 In vivo performance of the O-2 microsensors is dem onstrated by measurements of local changes in O-2 in the brain of anestheti zed rat before and during transient ischemia.