title: In vitro and in vivo investigations of upconversion and NIR emitting Gd₂O₃:Er³⁺,Yb³⁺ nanostructures for biomedical applications.
abstract: The use of an "over 1000-nm near-infrared (NIR) in vivo fluorescence bioimaging" system based on lanthanide containing inorganic nanostructures emitting in the visible and NIR range under 980-nm excitation is proposed. It may overcome problems of currently used biomarkers including color fading, phototoxicity and scattering. Gd(2)O(3):Er(3+),Yb(3+) nanoparticles and nanorods showing upconversion and NIR emission are synthesized and their cytotoxic behavior is investigated by incubation with B-cell hybridomas and macrophages. Surface modification with PEG-b-PAAc provides the necessary chemical durability reducing the release of toxic Gd(3+) ions. NIR fluorescence microscopy is used to investigate the suitability of the nanostructures as NIR-NIR biomarkers. The in vitro uptake of bare and modified nanostructures by macrophages is investigated by confocal laser scanning microscopy. In vivo investigations revealed nanostructures in liver, lung, kidneys and spleen a few hours after injection into mice, while most of the nanostructures have been removed from the body after 24 h.
authors.affiliation: Center for Technologies Against Cancer, Tokyo University of Science, 2669 Yamazaki, Chiba 278-0022, Japan. eva.hemmer@sogalabo.jp
authors.forename: Eva
authors.initials: E
authors.lastname: Hemmer
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Takeshita
authors.forename: Tomoyoshi
authors.initials: T
authors.lastname: Yamano
authors.forename: Takanori
authors.initials: T
authors.lastname: Fujiki
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Kohl
authors.forename: Karin
authors.initials: K
authors.lastname: Löw
authors.forename: Nallusamy
authors.initials: N
authors.lastname: Venkatachalam
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hyodo
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Kishimoto
authors.forename: Kohei
authors.initials: K
authors.lastname: Soga
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D002460:Cell Line; D002470:Cell Survival; D004871:Erbium / Q000737:chemistry* / Q000493:pharmacokinetics; D005682:Gadolinium / Q000737:chemistry* / Q000493:pharmacokinetics; D066298:In Vitro Techniques; D051379:Mice; D008855:Microscopy, Electron, Scanning; D049329:Nanostructures; D033362:Powder Diffraction; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D013499:Surface Properties; D014018:Tissue Distribution; D015018:Ytterbium / Q000737:chemistry* / Q000493:pharmacokinetics
chemical_list: D001672:Biocompatible Materials; C030581:gadolinium oxide; D004871:Erbium; D005682:Gadolinium; D015018:Ytterbium