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Abstract  

The purpose of this work was to indirect label IgG with fac-[188Re(CO)3(H2O)3]+ and to check the radiochemical behavior of the labeled product. The compound of (bis(2-pyridylmethyl)-amino)-acetic acid (L2H) was synthesized and labeled with fac-[188Re(CO)3(H2O)3]+. The labeling yield of 188Re(CO)3–L2H was more than 90%. The effects of protein concentration, reaction time, pH and reaction temperature of labeling of IgG with 188Re(CO)3–L2H were investigated. The conjugation conditions were optimized. The labeled product was analyzed by size exclusion HPLC and TLC. The stability of 188Re(CO)3–L2H–IgG in vitro was high. The results of this study may be useful for [188Re(CO)3(H2O)3]+ labeling of protein for radioimmunotherapy.

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Abstract  

Improved radionuclide generator include a substantially insoluble salt of a radioactive parent which may be directly packed in column for subsequent elution of the daughter radionuclide. An improved 188Re generator was prepared by reacting a radioactive tungsten (188W) as parent radionuclide incorporated with aluminum chloride to obtain an insoluble radioactive aluminum tungstate matrix. The investigated matrix was characterized on the basis of the chemical composition, IR, thermal analysis and mechanical stabilities. The factors affecting the elution performance were studied such as influence of pH, molar ratio and drying temperature. From the obtained data, the molar ratio W:Al was 1.5:1 at pH = 4, the matrix dried at 105 °C for 2 h. Chromatographic and multichannel analysis has been currently used to investigate the radiochemical and radionuclidic purity respectively on eluted 188Re. An elution yield more than 80%, with radiochemical purity <98% and radionuclidic purity <99% with a 188W break through >10−4% of the column. The Al+3 and W contents value were about 2 and 3 μg/mL eluate. The obtained data approved the stability of the prepared generator and its suitability for medical application.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: L. Zhou, S. Wen, J. Zhao, B. Yu, B. Han, and Ch. Yang

Abstract  

The -ray spectra of188Re decay have been studied by using two Ge/Li/ spectrometers and a three parameters /E-E-T/ List coincidence system. The energies and relative intensities of 52 -rays and cascade relations of 14 -rays are determined. Ten new -rays: 155 /633–478/, 984, 1096, 1463, 1332, 1530, 1574, 1810, 1867, and 1937 keV have been identified. The 155 /633–478/ transition is confirmed and its relative intensity is estimated by means of coincidence experiment. 24 levels of188Re are assigned. Among those, 6 levels are first put into the decay scheme of188Re. In addition to 1443 keV and 1937 keV levels, 1685, 1729 and 1965 keV levels are also observed in the decay of188Ir and other reaction studies. The 1948 level is recently suggested in the190Os/p, t/188Os reaction. The 486 keV and 811 keV -transitions are also put into the level scheme of188Re. The decay branching ratio is deduced.

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Abstract  

Labeling of diethylenetriamine-N,N,N′,N″,N″-pentakis(methylenephosphonic) acid (DTPMP) with rhenium-188 using stannous chloride as a reducing agent has been investigated. Dependence of the yield of the 188Re–DTPMP complex on the concentration of the reducing agent, pH, reaction time, temperature, ascorbic acid and amount of carrier added has been studied. Under optimum conditions, the labeling yield of 188Re–DTPMP complex is 95% for the carrier-free 188Re but with the carrier-added 188Re the labeling yield is more than 97%. Furthermore, the stability of the 188Re–DTPMP complex against pH change and dilution with saline has been also studied. It is found that the addition of carrier stabilizes the 188Re–DTPMP complex against pH change and dilution.

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Abstract  

Gel generators based on Zn, Co, Ni, Mn and Pb tungstates were prepared as potential supports for the development of188Re radiopharmaceuticals. Factors which affected either the elution efficiency of188Re or the breakthrough of188W were examined.188Re was produced as perrenate when the generators were eluted with saline (0.15M NaCl) and different organic solvents. The elution yield of188Re decreased for the various gel supports as: Zn (75%), Co (60%), Ni (37%), Mn (24%), Pb (15%). When a tandem system comprised of a chromatographic alumina column was utilized in combination with the gel generator the188W breakthrough was controlled to of the order of 10–6%.

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Abstract  

Hydroxyapatite (HA), a natural constituent of bone, was synthesized. HA particles were radiolabeled with 188Re. Radiolabeling efficiency was 95%. In vitro studies showed 5% loss of activity from particles in normal saline over a period of 2 days, whereas a dissociation rate of 9% was observed in human serum albumin.

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Abstract  

Twenty clinical scale alumina-based 188W/188Re generators and carrier-free 188Re has been produced at the Institute of Nuclear Energy Research (INER-Taiwan) for over ten years. 2845.6 GBq (76.9 Ci) of 188Re-perrhenate solution has been eluted from generators during the past ten years. We have used the harvesting 188Re solution for labeling radiopharmaceuticals, such as 188Re-HEDP, 188Re-MDP, 188Re-microsphere, 188Re-lipiodol, and 188Re-sulfur colloid, etc. The average eluting yield of 188Re is 78.6±5.8% that was investigated at 1115 harvesting times from 20 generators. Each generator can be used more than six months but the Millipore needs to be changed every two months for smooth harvesting and high yield of 188Re solution.

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Abstract  

The synthesis of 188Re-MAG3 is described using 188Re, which was obtained from the alumina based 188W/188Re generator. Dependence of the radiolabeling yields of 188Re-MAG3 on reducing agent concentration, Bz-MAG3 concentration, pH, temperature and incubation time was examined. In the case of optimum conditions the yield of 188Re-MAG3 was 98%. TLC and HPLC techniques were employed to monitor the different species formed. Biodistribution study of 188Re-MAG3 was carried out in rats and compared with behavior of 99mTc-MAG3.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: G. Ferro-Flores, F. Ramírez, M.G. Martínez-mendoza, C. Murphy, M. Pedraza-lópez, and L. García-salinas

Abstract  

Lanreotide peptide was labeled with 153Sm-H1ETA and 188Re-MAG3 in order to evaluate whether or not their conjugation to the peptide produce significant differences of the in vitro lipophilicity with respect to the 188Re-lanreotide prepared by the direct labeling method (highly lipophilic). The differences of lipophilicity between the complexes, were evaluated using a reverse phase HPLC system. The measured lipophilicity of 153Sm-H1ETA-lanreotide, 188Re-MAG3-lanreotide and 188Re-lanreotide was taken to be the capacity factor [k" = (t R-t 0)/t 0 where t R is the retention time and t 0 is the dead time] for each of the complexes under identical chromatography conditions. Results showed that the in vitro lipophilicity decreased in the order 188Re-lanreotide (direct labeling), 188Re-MAG3-lanreotide and 153Sm-H1ETA-lanreotide. Since the last one has a capacity factor (k") similar to that of 188Re-MAG3, some renal elimination for 153Sm-H1ETA-lanreotide could be expected, which probably would reduce the unnecessary radiation dose to normal tissues.

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Summary  

Fac-[188Re(CO)3(H2O)3]+ was synthesized with an overall radiochemical yield of 80±5%, and more than 95% radiochemical purity after a QMA Sep-Pak column separation. Fac-[Re(CO)3(H2O)3]+ was also synthesized as a reference sample. The structure of the precursor, fac-[188Re(CO)3(H2O)3]+, was confirmed by high performance of liquid chromatography (HPLC). MN-His (magnetic nanoparticles coated with silica and modified with an amino silane coupling agent, N-[3-(trimethyoxysilyl)propyl]-ethylenediamine (SG-Si900) and immobilized with histidine) was labeled with fac-[188Re(CO)3(H2O)3]+ and an initial animal test of MN-His was conducted for a magnetic targeting study.

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