title: (α-NaYbF4:Tm(3+))/CaF2 core/shell nanoparticles with efficient near-infrared to near-infrared upconversion for high-contrast deep tissue bioimaging.
abstract: We describe the development of novel and biocompatible core/shell (α-NaYbF(4):Tm(3+))/CaF(2) nanoparticles that exhibit highly efficient NIR(in)-NIR(out) upconversion (UC) for high contrast and deep bioimaging. When excited at ~980 nm, these nanoparticles emit photoluminescence (PL) peaked at ~800 nm. The quantum yield of this UC PL under low power density excitation (~0.3 W/cm(2)) is 0.6 ± 0.1%. This high UC PL efficiency is realized by suppressing surface quenching effects via heteroepitaxial growth of a biocompatible CaF(2) shell, which results in a 35-fold increase in the intensity of UC PL from the core. Small-animal whole-body UC PL imaging with exceptional contrast (signal-to-background ratio of 310) is shown using BALB/c mice intravenously injected with aqueously dispersed nanoparticles (700 pmol/kg). High-contrast UC PL imaging of deep tissues is also demonstrated, using a nanoparticle-loaded synthetic fibrous mesh wrapped around rat femoral bone and a cuvette with nanoparticle aqueous dispersion covered with a 3.2 cm thick animal tissue (pork).
authors.affiliation: School of Chemical Engineering and Technology, Harbin Institute of Technology, 150001 Harbin, People's Republic of China.
authors.forename: Guanying
authors.initials: G
authors.lastname: Chen
authors.forename: Jie
authors.initials: J
authors.lastname: Shen
authors.forename: Tymish Y
authors.initials: TY
authors.lastname: Ohulchanskyy
authors.forename: Nayan J
authors.initials: NJ
authors.lastname: Patel
authors.forename: Artem
authors.initials: A
authors.lastname: Kutikov
authors.forename: Zhipeng
authors.initials: Z
authors.lastname: Li
authors.forename: Jie
authors.initials: J
authors.lastname: Song
authors.forename: Ravindra K
authors.initials: RK
authors.lastname: Pandey
authors.forename: Hans
authors.initials: H
authors.lastname: Agren
authors.forename: Paras N
authors.initials: PN
authors.lastname: Prasad
authors.forename: Gang
authors.initials: G
authors.lastname: Han
mesh_terms: D000818:Animals; D002124:Calcium Fluoride; D003287:Contrast Media / Q000138:chemical synthesis*; D005269:Femur / Q000033:anatomy & histology*; D005459:Fluorides; D007259:Infrared Rays; D008422:Materials Testing; D051379:Mice; D008856:Microscopy, Fluorescence / Q000379:methods*; D008968:Molecular Conformation; D018482:Muscle, Skeletal / Q000033:anatomy & histology*; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D016062:Porosity; D051381:Rats; D013552:Swine; D015019:Yttrium
chemical_list: D003287:Contrast Media; C525362:sodium yttriumtetrafluoride; D015019:Yttrium; D002124:Calcium Fluoride; D005459:Fluorides