title: Dirhenium decacarbonyl-loaded PLLA nanoparticles: influence of neutron irradiation and preliminary in vivo administration by the TMT technique.
abstract: In a previous study, we have described the elaboration of PLLA-based nanoparticles loaded with non radioactive dirhenium decacarbonyl [Re(2)(CO)(10)], a novel neutron-activatable radiopharmaceutical dosage form for intra-tumoral radiotherapy. These nanoparticles are designed for a neutron irradiation which can be carried out in a nuclear reactor facility. This new paper describes the neutron irradiation influence on these Re(2)(CO)(10)-loaded PLLA nanoparticles. The loaded nanoparticles with 23% (w/w) of metallic rhenium have shown to remain stable and separated and to keep out their sphericity at the lower neutron flux (1x10(11)n/cm(2)/s for 0.5h) which was used for rhenium content determination (neutron activation analysis, NAA). However, when loaded nanoparticles were irradiated at the higher neutron flux (1.45x10(13)n/cm(2)/s, 1h), they have shown to be partially coagglomerated and some pores appeared at their surface. Furthermore, DSC results showed a decrease in the PLLA melting point and melting enthalpy in both blank and loaded nanoparticles indicating a decrease in polymer crystallinity. In addition, the polymer molecular weights (M(n), M(w)) decreased after irradiation but without largely affecting the polymer polydispersity index (P.I.) which indicated that an irradiation-induced PLLA chain scission had occurred in a random way. The XRD patterns of irradiated PLLA provided another proof of polymer loss of crystallinity. FTIR spectra results have shown that irradiated nanoparticles retained the chemical identity of the used Re(2)(CO)(10) and PLLA despite the reduction in polymer crystallinity and molecular weight. Nanoparticles suspending after irradiation became also more difficult, but it was properly achievable by adding PVA (1%) and ethanol (10%) into the dispersing medium. Moreover, after 24h incubation of different irradiated nanoparticles in two different culture mediums, visual examination did not show bacterial growth indicating that applied neutron irradiation, yielding an absorbed dose of 450kGy, can be a terminal method for nanoparticles sterilisation. Thereafter, in a preliminary in vivo experiment, superparamagnetic non radioactive nanoparticles loaded with Re(2)(CO)(10) and oleic-acid coated magnetite have been successfully injected into a mice animal model via targeted multi therapy (TMT) technique which would be our selected administration method for future in vivo studies. In conclusion, although some induced neutron irradiation damage to nanoparticles occurs, dirhenium decacarbonyl-loaded PLLA nanoparticles retain their chemical identity and remain almost as re-dispersible and injectable nanoparticles by the TMT technique. These nanoparticles represent a novel interesting candidate for local intra-tumoral radiotherapy.
authors: Pharmaceutics and Pharmaceutical Technology Department, LAGEP,Université Claude Bernard (Lyon1) UCB, CPE-Lyon, Faculté de Pharmacie Lyon1,France.
authors: Misara
authors: M
authors: Hamoudeh
authors: Hatem
authors: H
authors: Fessi
authors: Henri
authors: H
authors: Mehier
authors: Achraf Al
authors: AA
authors: Faraj
authors: Emmanuelle
authors: E
authors: Canet-Soulas
mesh_terms: D000818:Animals; D002152:Calorimetry, Differential Scanning; D005260:Female; D052203:Ferrosoferric Oxide / Q000737:chemistry; D006614:Hindlimb / Q000473:pathology / Q000528:radiation effects; D007273:Injections, Intramuscular; D019344:Lactic Acid / Q000737:chemistry*; D008279:Magnetic Resonance Imaging; D051379:Mice; D008815:Mice, Inbred Strains; D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight; D053758:Nanoparticles / Q000737:chemistry* / Q000528:radiation effects; D009502:Neutrons; D010316:Particle Size; D044367:Phase Transition / Q000528:radiation effects; D011091:Polyesters; D011108:Polymers / Q000737:chemistry*; D016062:Porosity / Q000528:radiation effects; D019275:Radiopharmaceuticals / Q000008:administration & dosage* / Q000737:chemistry; D012211:Rhenium / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013242:Sterilization; D013499:Surface Properties / Q000528:radiation effects; D044366:Transition Temperature / Q000528:radiation effects; D014961:X-Ray Diffraction
chemical_list: D011091:Polyesters; D011108:Polymers; D019275:Radiopharmaceuticals; D012997:Solvents; C526263:dirhenium decacarbonyl; D019344:Lactic Acid; C033616:poly(lactide); D012211:Rhenium; D052203:Ferrosoferric Oxide