title: Probing intracellular oxygen by quenched phosphorescence lifetimes of nanoparticles containing polyacrylamide-embedded [Ru(dpp(SO3Na)2)3]Cl2.
abstract: Methods for measuring O(2) within living cells that rely on luminescent probes are hampered by several factors: local conditions of hydrophobicity, pH, ionic composition, dielectric constant, and photobleaching by free radical species. Use of a polymer-embedded luminophore should minimize these problems. Here we use a Ru(II) coordination complex embedded within 45 nm hydrodynamic diameter nanoparticles, and demonstrate that both phosphorescence intensity and lifetimes are O(2)-sensitive, both in aqueous suspensions and intracellularly (e.g. 4.06 versus 1.55 microseconds under anaerobic or aerobic conditions, respectively). Electroporation is necessary for incorporation of the nanoparticles into yeasts: it is more effective with the fission yeast, Schizosaccharomyces pombe, than for the budding yeast, Saccharomyces cerevisiae. However, electroporation was not required for particle uptake into a cultured human cell-line (mammary adenosarcoma MCF-7), although the intracellular distribution of the probe is more general to intracellular compartments when electroporation is employed. These procedures did not compromise vitality of cells over periods of 6 h, as judged by retention of structural characteristics evident in Nomarski interference or confocal microscopy images. Spatial resolution of intracellular structures defined by nanoparticle phosphorescence intensity imaging indicates potential usefulness of the application of lifetime imaging techniques for mapping of intracellular O(2) distributions.
authors.affiliation: School of Chemistry, Cardiff University, Cardiff, Wales, UK CF10 3AT.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Coogan
authors.forename: Jonathan B
authors.initials: JB
authors.lastname: Court
authors.forename: Victoria L
authors.initials: VL
authors.lastname: Gray
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Hayes
authors.forename: Siôn H
authors.initials: SH
authors.lastname: Lloyd
authors.forename: Coralie O
authors.initials: CO
authors.lastname: Millet
authors.forename: Simon J A
authors.initials: SJ
authors.lastname: Pope
authors.forename: David
authors.initials: D
authors.lastname: Lloyd
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D000332:Aerobiosis; D000693:Anaerobiosis; D045744:Cell Line, Tumor; D018274:Electroporation; D006801:Humans; D042541:Intracellular Space / Q000378:metabolism*; D049408:Luminescent Agents / Q000737:chemistry* / Q000378:metabolism; D008163:Luminescent Measurements; D057054:Molecular Imaging; D053758:Nanoparticles / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry* / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D010618:Phenanthrolines / Q000737:chemistry* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology; D012568:Schizosaccharomyces / Q000166:cytology; D000099166:Polyacrylamides
chemical_list: D000180:Acrylic Resins; D049408:Luminescent Agents; D009942:Organometallic Compounds; D010100:Oxygen; D010618:Phenanthrolines; D000099166:Polyacrylamides; C518776:ruthenium II tris (bathophenanthroline disulfonate)