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Title:Fusinite: A Coal-Derived EPR Probe for Oxygen. Mechanism and Application in Vivo and in Vitro
Author(s):Vahidi, Navid
Doctoral Committee Chair(s):Clarkson, Robert B.
Department / Program:Center for Biophysics and Computational Biology
Discipline:Biophysics
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):Chemistry, Analytical
Chemistry, Physical
Biophysics, General
Abstract:Fusinite, an inertinite coal maceral, exhibits a symmetric and exchange-narrowed electron paramagnetic resonance (EPR) line (g = 2.00276), with a first derivative peak-to-peak linewidth $(\Delta$B) which is reversibly broadened by molecular O$\sb2.$
To explain the mechanism of this type of broadening, pulse and multifrequency EPR measurements (0.25-250 GHz) were carried out in conjunction with O$\sb2$ adsorption isotherm studies.
The data suggest that, at ambient temperatures, homogeneous broadening of the EPR line of fusinite probably occurs by the exchange modulation of a group of delocalized unpaired electrons at the surface of fusinite by physically adsorbed O$\sb2.$ At temperatures below 260$\sp\circ$ K, dipole-dipole mechanisms begin to contribute more significantly to the broadening of this component. The presence of another O$\sb2$-dependent component, with a much broader linewidth, but an identical g-value, is borne out by more careful analysis of the total spectrum and theoretical considerations. The possibility of two different classes of sites for interaction with O$\sb2$ is discussed.
The extent of broadening per unit concentration of molecular oxygen (d$\Delta$B/d(O$\sb2$)) is unusually large, exceeding that of nitroxides by almost two orders of magnitude at physiological temperature and concentration ranges. This paramagnetic property of fusinite, combined with its very stable physicochemical properties and low toxicity, is of utility for the measurement of the concentration of oxygen or (O$\sb2$) in vivo and in vitro.
Fusinite particles, when prepared in subcellular dimensions, can be endocytosed by chinese hamster ovary (CHO) cells in vitro. This is useful for intracellular measurements of (O$\sb2$) with commercially available EPR spectrometers operating at 9.1-9.3 GHz. For in vivo measurements of (O$\sb2$) with low frequency EPR (1.1-1.3 GHz), fusinite provides a sensitive and persistent means to measure (O$\sp2$). Fusinite particles were implanted into the gastrocnemius muscle of A/J mice; these particles remained interstitially in the same position for months with undiminished sensitivity to (O$\sb2$) and no specific toxic effects.
Due to the special properties of the surface of fusinite, in the aqueous environment of cells and tissues, $\Delta$B is an indicator of the partial pressure of O$\sb2$ (P$\sb{\rm O2})$ rather than (O$\sb2$). Therefore, fusinite is especially useful when the solubility of O$\sb2$ in the surrounding medium is unknown.
Issue Date:1993
Type:Text
Description:119 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1993.
URI:http://hdl.handle.net/2142/72408
Other Identifier(s):(UMI)AAI9329189
Date Available in IDEALS:2014-12-17
Date Deposited:1993


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