Electrochemical measurement of endogenously produced nitric oxide in brain slices using Nafion/o-phenylenediamine modified carbon fiber microelectrodes

Abstract

The role of nitric oxide ( • NO) as a regulatory diffusible molecule in the brain requires the evaluation of its concentration dynamics. In this work, we have developed microelectrodes suitable for real time electrochemical measurements of • NO in vitro. Nafion and o-phenylenediamine were used to modify the surface of carbon fiber microelectrodes (8 m diameter; ≈100 m tip length). Coating with Nafion was done at 170 • C and the o-phenylenediamine solution was electropolimerized on the carbon surface. • NO peak potential (+0.78 ± 0.03 V versus Ag/AgCl) was determined by square wave voltammetry with • NO solutions prepared from the-generating compound diethylenetriamine/nitric oxide (DETA/NO). Microelectrodes were calibrated by amperometry at a potential of +0.90 V versus Ag/AgCl. They showed good sensitivity (954 ± 217 pA/M; n = 6) and linearity to • NO in the concentration range of 100-1000 nM. They were also characterized in terms of detection limit (6 ± 2 nM, n = 4), response time at 50% (1 s), and selectivity against interferents, such as nitrite (780 ± 84:1, n = 6), ascorbic acid (750 ± 187:1, n = 6) or dopamine (18 ± 2:1, n = 6). Injections of 1 mM l-glutamate, 1 mM l-arginine, and 0.1 mM N-methyl-d-aspartate did not produce changes in background current. Finally, the microelectrodes were used to measure • NO concentration dynamics in rat hippocampal brain slices stimulated with l-glutamate and N-methyl-d-aspartate. Taken together, the data indicate that the microelectrodes exhibit the proper sensitivity and selectivity for studies of • NO dynamics in brain slices (in vitro) and possibly in whole brain (in vivo) recordings.

Ascorbic Acid Rejection Characteristics of Modified Platinum Electrodes: A Shelf Life Investigation

“…Therefore it is plausible that this translates to the results described within, whereby salts from the PBS electrolyte adsorb on the Nafion ® surface after repeated exposure, compromising its integrity over time. Previously, a number of groups have investigated the simultaneous combination of Nafion ® and PPD on carbon fiber electrodes in the expectation of improving sensor performance [6,16,17,39]. Two variations of this polymer combination were investigated and the results are presented in Table 1.…”

“…A number of previous reports have detailed the excellent permselective properties of electrochemical sensors that incorporate both Nafion ® and PPD layers in their membrane design [6,16,17]. It is…”

Tonic and stimulus-evoked nitric oxide production in the mouse olfactory bulb

“…Methods for electrochemical detection of NO have recently become available (Wink et al, 1995;Christodoulou et al, 1996;Allen et al, 2000;Brunet et al, 2003;Zhang, 2004;Nunemaker et al, 2007), enabling measurements of NO on the second and sub-second time scales in local regions of neural circuitry in vivo (Buerk et al, 1996;Buerk et al, 2003a;Buerk et al, 2003b), in brain slices in vitro (Leonard et al, 2001;Ledo et al, 2002;Ferreira et al, 2005) and in neuronal cell cultures (Oni et al, 2004;Xu et al, 2004;Pereira-Rodriques et al, 2005). Here, we show for the first time that NO-selective microelectrodes can be used to measure NO production in the living mouse olfactory bulb.…”

Stimulation of NMDA and AMPA glutamate receptors elicits distinct concentration dynamics of nitric oxide in rat hippocampal slices

“…Microsensors were prepared as previously described (Barbosa et al, 1998;Ledo et al, 2002;Ferreira et al, 2005). Briefly, single carbon fibers (8 lm i.d.…”