Sol−Gel Derived Amperometric Nitric Oxide\nMicrosensor

Abstract

An amperometric sol−gel derived nitric oxide microsensor is described. Several silicon-based xerogel membranes are evaluated to identify the optimum composition\nfor maximizing NO permeability while providing sufficient\nselectivity for NO in the presence of common interfering\nspecies. Xerogel permeability and selectivity are further\nmanipulated as a function of reaction/processing conditions. In addition, the effects of incorporating Nafion into\nthe xerogel matrix on sensor performance and the stability\nof the ensuing xerogel/Nafion hybrid film are evaluated.\nThe optimal permselective membrane is achieved by\ncatalyzing polycondensation of the xerogel composed of\nmethyltrimethoxysilane and (aminoethylaminomethyl)phenethyltrimethoxysilane and Nafion with NO gas. The\nresulting NO microsensor exhibits a sensitivity of 0.17 ±\n0.02 pA/nM (from 25 to 800 nM, <i>r</i> = 0.9991), detection\nlimit of 25 nM (S/N = 3), response time of 9 s (<i>t</i>_95%, a\nNO concentration change from 400 to 500 nM), selectivity (log\n\n\n) of −5.8, <−6, <−6, and <−6 for <i>j</i> =\nnitrite, ascorbic acid, uric acid, and acetaminophen, and\na lifetime of 8 d (82% of initial sensitivity without serious\ndeterioration in selectivity).