title: Molecular oxygen-sensitive fluorescent lipobeads for intracellular oxygen measurements in murine macrophages.
abstract: 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.
authors.affiliation: Department of Chemistry, University of New Orleans, Louisiana 70148, USA.
authors.forename: J
authors.initials: J
authors.lastname: Ji
authors.forename: N
authors.initials: N
authors.lastname: Rosenzweig
authors.forename: I
authors.initials: I
authors.lastname: Jones
authors.forename: Z
authors.initials: Z
authors.lastname: Rosenzweig
mesh_terms: D015082:2,2'-Dipyridyl / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry; D000818:Animals; D002478:Cells, Cultured; D005456:Fluorescent Dyes / Q000032:analysis*; D018496:Hyperoxia / Q000378:metabolism; D000860:Hypoxia / Q000378:metabolism; D007103:Immobilization; D008264:Macrophages / Q000737:chemistry* / Q000166:cytology; D051379:Mice; D009942:Organometallic Compounds / Q000032:analysis / Q000737:chemistry; D018384:Oxidative Stress / Q000502:physiology; D010100:Oxygen / Q000032:analysis* / Q000737:chemistry* / Q000378:metabolism; D010587:Phagocytosis / Q000502:physiology; D010743:Phospholipids / Q000737:chemistry
chemical_list: D005456:Fluorescent Dyes; D009942:Organometallic Compounds; D010743:Phospholipids; C095931:dichlorobis(2,2'-bipyridine)ruthenium; C439588:trisbypyridine-4(1''''-pyrenyl)-2,2'-bipyridineruthenium chloride; D015082:2,2'-Dipyridyl; D010100:Oxygen