Mechanism of Oxygen Response in Carbon-Based Sensors

Ацаркин, В. А.; Демидов, В. В.; Vasneva, G. A.; Dzheparov, F. S.; Ceroke, P.J.; Odintsov, B. M.; Clarkson, R. B.

doi:10.1006/jmre.2000.2274

Cited by 30 publications

(31 citation statements)

References 11 publications

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“…139 The mechanism of oxygen response has been studied in several synthesized chars. The results suggest that these compounds contain two types of paramagnetic centers (PC), 140,141 differing by their distance to the adsorbed oxygen molecules. Each type of PC is characterized by its own oxygen sensitivity and EPR linewidth.…”

Section: Principles Of Epr Oximetrymentioning

confidence: 99%

“…When the oxygen exceeds 3 mM, the twodimensional dipole-dipole interactions between the paramagnetic centers come into play, and results in a change in broadening as well as in changes in EPR lineshape. 141 In practice, a given paramagnetic material (soluble radicals or particulates) can be calibrated in terms of the effect of oxygen on the linewidth (Fig. 2).…”

Section: Principles Of Epr Oximetrymentioning

confidence: 99%

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Assessment of tumor oxygenation by electron paramagnetic resonance: principles and applications

2004

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This review paper attempts to provide an overview of the principles and techniques that are often termed electron paramagnetic resonance (EPR) oximetry. The paper discusses the potential of such methods and illustrates they have been successfully applied to measure oxygen tension, an essential parameter of the tumor microenvironment. To help the reader understand the motivation for carrying out these measurements, the importance of tumor hypoxia is first discussed: the basic issues of why a tumor is hypoxic, why these hypoxic microenvironments promote processes driving malignant progression and why hypoxia dramatically influences the response of tumors to cytotoxic treatments will be explained. The different methods that have been used to estimate the oxygenation in tumors will be reviewed. To introduce the basics of EPR oximetry, the specificity of in vivo EPR will be discussed by comparing this technique with NMR and MRI. The different types of paramagnetic oxygen sensors will be presented, as well as the methods for recording the information (EPR spectroscopy, EPR imaging, dynamic nuclear polarization). Several applications of EPR for characterizing tumor oxygenation will be illustrated, with a special emphasis on pharmacological interventions that modulate the tumor microenvironment. Finally, the challenges for transposing the method into the clinic will also be discussed.

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Section: Principles Of Epr Oximetrymentioning

confidence: 99%

Section: Principles Of Epr Oximetrymentioning

confidence: 99%

Assessment of tumor oxygenation by electron paramagnetic resonance: principles and applications

2004

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“…The broadening of the ESR spectrum in the presence of molecular oxygen is generally attributed to the Heisenberg spin exchange between the LiNc-BuO probe and molecular oxygen, and subsequent shortening of the spin-spin relaxation time. 18,19 The variation of the peak-to-peak width with pO2 observed for LiNc-BuO is shown in Fig. 1B.…”

Section: Resultsmentioning

confidence: 99%

Measuring Brain Tissue Oxygenation under Oxidative Stress by ESR/MR Dual Imaging System

et al. 2007

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The in vivo measurement of oxygen in tissues is of great interest because of oxygen's fundamental role in life. Many methods have been developed for such measurement, but all have been limited, especially with regard to repeated measurement, degree of invasiveness, and sensitivity. We describe electron spin resonance (ESR) oximetry with paramagnetic oxygen-sensing probe for in vivo measurement of oxygen in brain tissues by homemade ESR W MR dual imaging spectroscopy. Lithium 5, 9, 14, 18, 23, 27, 32, 36-octan-butoxy-2,3-naphthlocyanine (LiNc-BuO) radical was employed as the solid oxygensensing probe, and we conˆrmed its ability to report partial pressure of oxygen (pO 2 ) in brain tissues of live animals under normal and pathological conditions for more than a month. pO 2 measurements could also be made repeatedly on the same animal and at the same location. The implantation site of LiNc-BuO in examined rats was veriˆed by 0.5T magnetic resonance (MR) imaging. Septic-shock rats were used to monitor tissue oxygenation during pathological state. A decline in pO 2 levels from severe hypotension during sepsis was detected, and generation of nitric oxide (NO) in brain tissues was conˆrmed by NO spin trapping. ESR oximetry using oxygen-sensing probe and NO spintrapping can be used to monitor pO 2 change and NO production simultaneously and repeatedly at the same site in examined animals.

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“…The measurement of the oxygen concentration c is based on measuring the line width and/or amplitude of the electron paramagnetic resonance (EPR) signal, both parameters being extremely sensitive to the adsorbed 0 2 molecules. In studies of the relationship between the EPR lineshape and the oxygen concentration in the environment [3][4][5], we observed that the EPR spectrum in the chars can be described by superposition of two lines with nearly equal g-factors belonging to two types of PCs (called A and B). Both A and B centers are placed near the char surface; this fact was proved by detailed analysis of the EPR lineshape, especially at its distant wings which were found to be typical of the two=dimensional distribution of PCs [4,5].…”

Section: Introductionmentioning

confidence: 99%

“…In studies of the relationship between the EPR lineshape and the oxygen concentration in the environment [3][4][5], we observed that the EPR spectrum in the chars can be described by superposition of two lines with nearly equal g-factors belonging to two types of PCs (called A and B). Both A and B centers are placed near the char surface; this fact was proved by detailed analysis of the EPR lineshape, especially at its distant wings which were found to be typical of the two=dimensional distribution of PCs [4,5]. The only difference between A and B centers is their different locations in the char structure andas a result their different geometrical distances from the adsorbed oxygen molecules.…”

Section: Introductionmentioning

confidence: 99%

Oxygen effect on spin relaxation of the surface paramagnetic centers in carbon chars

et al. 2005

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The original technique with the use of longitudinal electron paramagnetic resonance detection was applied to measure longitudinal and transversal electron relaxation times (T~ and 7".,) in specially prepared carbon chars containing paramagnetic centers (PCs) on the surface. The results not only confirmed the conclusions of our previous studies but enabled us to determine the exchange integral and clarify the mechanism of interaction between the PCs and adsorbed molecular oxygen O z. A spin relaxation mechanism .was also suggested which takes into account both the exchange and dipolar interactions in the systems combining PC and 02. The value of the excbange integral between PCs as well as its functional dependence on the oxygen content were estimated.

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Mechanism of Oxygen Response in Carbon-Based Sensors

Cited by 30 publications

References 11 publications

Assessment of tumor oxygenation by electron paramagnetic resonance: principles and applications

Assessment of tumor oxygenation by electron paramagnetic resonance: principles and applications

Measuring Brain Tissue Oxygenation under Oxidative Stress by ESR/MR Dual Imaging System

Oxygen effect on spin relaxation of the surface paramagnetic centers in carbon chars

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