title: Holmium nanoparticles: preparation and in vitro characterization of a new device for radioablation of solid malignancies.
abstract: OBJECTIVE
  The present study introduces the preparation and in vitro characterization of a nanoparticle device comprising holmium acetylacetonate for radioablation of unresectable solid malignancies.
  
  
  METHODS
  HoAcAc nanoparticles were prepared by dissolving holmium acetylacetonate in chloroform, followed by emulsification in an aqueous solution of a surfactant and evaporation of the solvent. The diameter, surface morphology, holmium content, and zeta potential were measured, and thermal behavior of the resulting particles was investigated. The stability of the particles was tested in HEPES buffer. The r(2)* relaxivity of protons and mass attenuation coefficient of the nanoparticles were determined. The particle diameter and surface morphology were studied after neutron activation.
  
  
  RESULTS
  Spherical particles with a smooth surface and diameter of 78 ± 10 nm were obtained, and the particles were stable in buffer. Neutron irradiation did not damage the particles, and adequate amounts of activity were produced for nuclear imaging and radioablation of malignancies through intratumoral injections.
  
  
  CONCLUSIONS
  The present study demonstrates that HoAcAc nanoparticles were prepared using a solvent evaporation process. The particle diameter can easily be adapted and can be optimized for specific therapeutic applications and tumor types.
authors.affiliation: Department of Radiology and Nuclear Medicine, Imaging Division, University Medical Centre Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands.
authors.forename: Wouter
authors.initials: W
authors.lastname: Bult
authors.forename: Rosanne
authors.initials: R
authors.lastname: Varkevisser
authors.forename: Fouad
authors.initials: F
authors.lastname: Soulimani
authors.forename: Peter R
authors.initials: PR
authors.lastname: Seevinck
authors.forename: Hendrik
authors.initials: H
authors.lastname: de Leeuw
authors.forename: Chris J G
authors.initials: CJ
authors.lastname: Bakker
authors.forename: Peter R
authors.initials: PR
authors.lastname: Luijten
authors.forename: Alfred D
authors.initials: AD
authors.lastname: van Het Schip
authors.forename: Wim E
authors.initials: WE
authors.lastname: Hennink
authors.forename: J Frank W
authors.initials: JF
authors.lastname: Nijsen
mesh_terms: D055011:Ablation Techniques / Q000295:instrumentation / Q000379:methods*; D006695:Holmium / Q000008:administration & dosage* / Q000737:chemistry; D006801:Humans; D015552:Injections, Intralesional; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles / Q000008:administration & dosage / Q000737:chemistry*; D009369:Neoplasms / Q000532:radiotherapy*; D010316:Particle Size; D011868:Radioisotopes; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties
chemical_list: D011868:Radioisotopes; D006695:Holmium