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Issue 10, 2009
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Nitric oxide monitoring in brain extracellular fluid: characterisation of Nafion®-modified Pt electrodes in vitro and in vivo

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Abstract

A Nafion®(5 pre-coats/2 dip-coats)-modified Pt sensor developed for real-time neurochemical monitoring has now been characterised in vitro for the sensitive and selective detection of nitric oxide (NO). A potentiodynamic profile at bare Pt established +0.9 V (vs. SCE) to be the most appropriate applied potential for NO oxidation. The latter was confirmed using oxyhaemoglobin and N2, both of which reduced the NO signal to baseline levels. Results indicated enhanced NO sensitivity at the Nafion®(5/2) sensor (1.67 ± 0.08 nA µM−1) compared to bare Pt (1.08 ± 0.20 nA µM−1) and negligible interference from a wide range of endogenous electroactive interferents such as ascorbic acid, dopamine and its metabolites, NO2 and H2O2. The response time of 33.7 ± 2.7 s was found to improve (19.0 ± 3.4 s) when the number of Nafion® layers was reduced to 2/1 and an insulating outer layer of poly(o-phenylenediamine) added. When tested under physiological conditions of 37 °C the response time of the Nafion®(5/2) sensor improved to 14.00 ± 2.52 s. In addition, the NO response was not affected by physiological concentrations of O2 despite the high reactivity of the two species for each other. The limit of detection (LOD) was estimated to be 5 nM while stability tests in lipid (phosphatidylethanolamine; PEA) and protein (bovine serum albumin; BSA) solutions (10%) found an initial ca. 38% drop in sensitivity in the first 24 h which remained constant thereafter. Preliminary in vivo experiments involving systemic administration of NO and L-arginine produced increases in the signals recorded at the Nafion®(5/2) sensor implanted in the striatum of freely-moving rats, thus supporting reliable in vivo recording of NO.

Graphical abstract: Nitric oxide monitoring in brain extracellular fluid: characterisation of Nafion®-modified Pt electrodes in vitro and in vivo

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Publication details

The article was received on 08 May 2009, accepted on 31 Jul 2009 and first published on 14 Aug 2009


Article type: Paper
DOI: 10.1039/B909005C
Analyst, 2009,134, 2012-2020

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    Nitric oxide monitoring in brain extracellular fluid: characterisation of Nafion®-modified Pt electrodes in vitro and in vivo

    F. O. Brown, N. J. Finnerty and J. P. Lowry, Analyst, 2009, 134, 2012
    DOI: 10.1039/B909005C

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