title: Characterization of poly(L-lactic acid) microspheres loaded with holmium acetylacetonate.
abstract: Holmium-loaded PLLA microspheres are useful systems in radioembolization therapy of liver metastases because of their low density, biodegradability and favourable radiation characteristics. Neutron activated Ho-loaded microspheres showed a surprisingly low release of the relatively small holmium complex. In this paper factors responsible for this behaviour are investigated, in particular by the use of differential scanning calorimetry, scanning electron microscopy, infrared spectroscopy and X-ray diffraction. The holmium complex is soluble in PLLA up to 8% in films and 17% in microspheres. Interactions between carbonyl groups of PLLA, and the Ho-ion in the HoAcAc complex, explain very satisfactorily the high stability of holmium-loaded microspheres.
authors.affiliation: Department of Nuclear Medicine, University Medical Centre Utrecht, The Netherlands. f.nijsen@ng.azu.nl
authors.forename: J F
authors.initials: JF
authors.lastname: Nijsen
authors.forename: M J
authors.initials: MJ
authors.lastname: van Steenbergen
authors.forename: H
authors.initials: H
authors.lastname: Kooijman
authors.forename: H
authors.initials: H
authors.lastname: Talsma
authors.forename: L M
authors.initials: LM
authors.lastname: Kroon-Batenburg
authors.forename: M
authors.initials: M
authors.lastname: van De Weert
authors.forename: P P
authors.initials: PP
authors.lastname: van Rijk
authors.forename: A
authors.initials: A
authors.lastname: De Witte
authors.forename: A D
authors.initials: AD
authors.lastname: Van Schip
authors.forename: W E
authors.initials: WE
authors.lastname: Hennink
mesh_terms: D001672:Biocompatible Materials; D002152:Calorimetry, Differential Scanning; D004621:Embolization, Therapeutic / Q000379:methods; D006695:Holmium / Q000008:administration & dosage*; D006801:Humans; D006885:Hydroxybutyrates / Q000008:administration & dosage; D066298:In Vitro Techniques; D019344:Lactic Acid; D008113:Liver Neoplasms / Q000532:radiotherapy / Q000556:secondary; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D010422:Pentanones / Q000008:administration & dosage; D011091:Polyesters; D011108:Polymers; D013055:Spectrophotometry, Infrared; D014961:X-Ray Diffraction
chemical_list: D001672:Biocompatible Materials; D006885:Hydroxybutyrates; D010422:Pentanones; D011091:Polyesters; D011108:Polymers; C049529:acetyl acetonate; D019344:Lactic Acid; C033616:poly(lactide); D006695:Holmium