title: Functional up-converting SrTiO3:Er(3+)/Yb(3+) nanoparticles: structural features, particle size, colour tuning and in vitro RBC cytotoxicity.
abstract: SrTiO3 nanoparticles co-doped with a broad concentration range of Er(3+) and Yb(3+) ions were fabricated using the citric route as a function of annealing temperatures of 500-1000 °C. The effect of a broad co-dopant concentration range and sintering temperature on structural and up-conversion properties was investigated in detail by X-ray diffraction techniques and optical spectroscopy. The TEM technique was used to estimate the mean particle size, which was around 30 nm for the inorganic product annealed at 600 °C. Up-conversion emission color tuning was achieved by particle size control. Power dependence of the green and red emissions was found to be a result of temperature determination in the operating range of SrTiO3 nanoparticles and a candidate for the fast and local microscopic heating and heat release induced by IR irradiation. The color changed from white-red-yellow-green upon an increase of sintering temperature, inducing changes in the surface-to-volume ratio and the number of optically active ions in particle surface regions. The cytotoxic activity of nanoparticles on human red blood cells was investigated, showing no harmful effects up to a particle concentration of 0.1 mg ml(-1). The cytotoxic response of a colloidal suspension of nanoparticles to RBC cells was connected with the strong affinity of SrTiO3 particles to the cell membranes, blocking the transport of important biological solutes.
authors.affiliation: Institute of Low Temperature and Structure Research, PAS, Okólna 2, 50-422 Wrocław, Poland. R.Pazik@int.pan.wroc.pl.
authors.forename: R
authors.initials: R
authors.lastname: Pazik
authors.forename: M
authors.initials: M
authors.lastname: Maczka
authors.forename: M
authors.initials: M
authors.lastname: Malecka
authors.forename: L
authors.initials: L
authors.lastname: Marciniak
authors.forename: A
authors.initials: A
authors.lastname: Ekner-Grzyb
authors.forename: L
authors.initials: L
authors.lastname: Mrowczynska
authors.forename: R J
authors.initials: RJ
authors.lastname: Wiglusz
mesh_terms: D001799:Blood Sedimentation; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003116:Color; D004871:Erbium / Q000737:chemistry* / Q000494:pharmacology; D004912:Erythrocytes / Q000187:drug effects; D006801:Humans; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D010087:Oxides / Q000737:chemistry* / Q000494:pharmacology; D010316:Particle Size; D013324:Strontium / Q000737:chemistry* / Q000494:pharmacology; D014025:Titanium / Q000737:chemistry* / Q000494:pharmacology; D015018:Ytterbium / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D010087:Oxides; D004871:Erbium; D014025:Titanium; D015018:Ytterbium; C119252:strontium titanium oxide; D013324:Strontium