Molecular oxygen-sensitive fluorescent lipobeads for intracellular oxygen measurements in murine macrophages.

J Ji, N Rosenzweig, I Jones, Z Rosenzweig

Department of Chemistry, University of New Orleans, Louisiana 70148, USA.

Analytical chemistry 2001 Aug 1

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Intracellular oxygen concentration is of primary importance in determining numerous physiological and pathological processes in biological systems. This paper describes the development and application of micrometer-sized oxygen-sensitive fluorescence lipobeads for intracellular measurements of molecular oxygen in J774 murine macrophages. A ruthenium diimine complex [Ru(bpy-pyr)(bpy)2]C12 (bpy = 2,2'-bipyridine, bpy-pyr = 4-(1"-pyrenyl)-2,2'-bipyridine) is used as the oxygen indicator. The indicator exhibits high chemical and photostability and high sensitivity to oxygen. The indicator molecules are immobilized in a phospholipid membrane that coats polystyrene microparticles. The fluorescence of the lipobeads is effectively quenched by molecular oxygen. The fluorescence intensity of the oxygen-sensitive lipobeads is 3 times higher in a nitrogenated solution than in an oxygenated solution. The lipobeads are internalized by murine macrophages through phagocytosis. They maintain their spectral properties for 24 h in living cells when the cells are stored in phosphate-buffered saline at pH 7.4. The photostability, reversibility, and effect of hypoxia, hyperoxia, and oxidative stress on the intracellular level of oxygen in J774 murine macrophages are described.

Citation

J Ji, N Rosenzweig, I Jones, Z Rosenzweig. Molecular oxygen-sensitive fluorescent lipobeads for intracellular oxygen measurements in murine macrophages. Analytical chemistry. 2001 Aug 1;73(15):3521-7