title: Enhancement of Cerenkov luminescence imaging by dual excitation of Er(3+),Yb(3+)-doped rare-earth microparticles.
abstract: Cerenkov luminescence imaging (CLI) has been successfully utilized in various fields of preclinical studies; however, CLI is challenging due to its weak luminescent intensity and insufficient penetration capability. Here, we report the design and synthesis of a type of rare-earth microparticles (REMPs), which can be dually excited by Cerenkov luminescence (CL) resulting from the decay of radionuclides to enhance CLI in terms of intensity and penetration.
  
  
  METHODS
  Yb(3+)- and Er(3+)- codoped hexagonal NaYF4 hollow microtubes were synthesized via a hydrothermal route. The phase, morphology, and emission spectrum were confirmed for these REMPs by power X-ray diffraction (XRD), scanning electron microscopy (SEM), and spectrophotometry, respectively. A commercial CCD camera equipped with a series of optical filters was employed to quantify the intensity and spectrum of CLI from radionuclides. The enhancement of penetration was investigated by imaging studies of nylon phantoms and nude mouse pseudotumor models.
  
  
  RESULTS
  the REMPs could be dually excited by CL at the wavelengths of 520 and 980 nm, and the emission peaks overlaid at 660 nm. This strategy approximately doubled the overall detectable intensity of CLI and extended its maximum penetration in nylon phantoms from 5 to 15 mm. The penetration study in living animals yielded similar results.
  
  
  CONCLUSIONS
  this study demonstrated that CL can dually excite REMPs and that the overlaid emissions in the range of 660 nm could significantly enhance the penetration and intensity of CL. The proposed enhanced CLI strategy may have promising applications in the future.
authors.affiliation: Department of Nuclear Medicine, Xijing Hospital, Fourth Military Medical University, Xi'an, PR China.
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Ma
authors.forename: Fei
authors.initials: F
authors.lastname: Kang
authors.forename: Feng
authors.initials: F
authors.lastname: Xu
authors.forename: Ailing
authors.initials: A
authors.lastname: Feng
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhao
authors.forename: Tianjian
authors.initials: T
authors.lastname: Lu
authors.forename: Weidong
authors.initials: W
authors.lastname: Yang
authors.forename: Zhe
authors.initials: Z
authors.lastname: Wang
authors.forename: Min
authors.initials: M
authors.lastname: Lin
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
mesh_terms: D000818:Animals; D003952:Diagnostic Imaging; D004871:Erbium / Q000737:chemistry*; D008163:Luminescent Measurements / Q000295:instrumentation*; D051379:Mice; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D009374:Neoplasms, Experimental / Q000175:diagnosis*; D019047:Phantoms, Imaging; D013053:Spectrophotometry; D014961:X-Ray Diffraction; D015018:Ytterbium / Q000737:chemistry*
chemical_list: D004871:Erbium; D015018:Ytterbium