title: Radiolabelling of poly(histidine) derivatized biodegradable microspheres with the 188Re tricarbonyl complex [188Re(CO)3(H2O)3]+.
abstract: OBJECTIVE
  Many radiopharmaceuticals have been studied as radiation synovectomy agents. In this study, we developed a new potential agent for radiation synovectomy: poly(lactic acid)-histidine (PLA-his) microspheres radiolabelled with [188Re(CO)3(H2O)3]+.
  
  
  METHODS
  The reaction conditions for the chelation of [188Re(CO)3(H2O)3]+ and the radiolabelling of PLA microspheres were optimized and the stabilities for both steps tested in vitro.
  
  
  RESULTS
  The chelation efficiency of [188Re(CO)3(H2O)3]+ reached 93.12 +/- 1.82% with >95% radiochemical purity once the colloidal and free 188Re were removed by a small Sep-Pak column (Plus QMA). More than 90% of radioactivity stayed in the [188Re(CO)3(H2O)3]+ form over 5 h. The radiolabelling efficiency of PLA-his microspheres with [188Re(CO)3(H2O)3]+ was above 92%. After 3 days incubation at 37 degrees C in calf serum, more than 80% of the radioactivity was still bound to the microspheres.
  
  
  CONCLUSIONS
  Such microspheres are potentially useful as a radiation synovectomy agent for the treatment of chronically inflamed arthritic joints. Furthermore, they might be valuable in cancer brachytherapy.
authors.affiliation: Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, PR China. yujfwyx@yahoo.com.cn
authors.forename: Junfeng
authors.initials: J
authors.lastname: Yu
authors.forename: Urs O
authors.initials: UO
authors.lastname: Häfeli
authors.forename: Jiaoyun
authors.initials: J
authors.lastname: Xia
authors.forename: Shiqiang
authors.initials: S
authors.lastname: Li
authors.forename: Mo
authors.initials: M
authors.lastname: Dong
authors.forename: Duanzhi
authors.initials: D
authors.lastname: Yin
authors.forename: Yongxian
authors.initials: Y
authors.lastname: Wang
mesh_terms: D001168:Arthritis / Q000473:pathology; D001672:Biocompatible Materials / Q000737:chemistry*; D001918:Brachytherapy / Q000379:methods; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D003102:Colloids; D006639:Histidine / Q000737:chemistry*; D006801:Humans; D007249:Inflammation; D008863:Microspheres; D011786:Quality Control; D011868:Radioisotopes / Q000737:chemistry; D019275:Radiopharmaceuticals / Q000737:chemistry; D012211:Rhenium / Q000737:chemistry; D013696:Temperature; D013997:Time Factors
chemical_list: D001672:Biocompatible Materials; D003102:Colloids; D011868:Radioisotopes; D019275:Radiopharmaceuticals; C033223:polyhistidine; D006639:Histidine; D012211:Rhenium