• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.1931-1935
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• 2011

The synthesis of carbocyclic analogues of normal nucleosides has grown exclusively since they have shown potential antiviral and antitumor activities. Radiolabeled cis-1-[4-(hydroxy-methyl)-cyclopent-2-enyl]-5-$[^{124}I]$-iodocytosine (carbocyclic d4IC) and cis-1-[4-(hydroxy-methyl)-cyclopent-2-enyl]-5-(2-$[^{124}I]$iodovinyl)cytosine(carbocyclic d4IVC) were synthesized. The synthetic route employed Pd(0)-catalyzed coupling reaction together with organotin and exchange reaction for radioiodination as key reactions. Carbocyclic $[^{124}I]$d4IC gave more than 75% radiochemical yield with greater than 95% radiochemical purity. Carbocyclic $[^{124}I]$d4IVC gave more than 80% radiochemical yield with greater than 95% radiochemical purity.

• Journal of Powder Materials
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• v.15 no.6
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• pp.466-470
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• 2008

Experiments with a URT-0.5 accelerator (0.5 MeV, 50 ns, 1 kW) generating a nanosecond electron beam for irradiation of silver nitrate in various liquid solutions (water and toluene) were performed with the aim of producing silver nanopowders. A radiochemical reaction allows making weakly agglomerated pure Ag powders with particles of 10-15 nm and 30-50 nm in size by irradiation in toluene and water respectively. The injection of the nanosecond electron beam energy to the solution is optimal. As the absorbed dose increases, the output of the radiochemical reaction does not grow, but more agglomerated powders are synthesized.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.3 no.1
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• pp.44-51
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• 2017

Herein we report an efficient radiolabeling method based on a rapid condensation reaction between N-terminal cysteine and 2-cyanobenzothiazole (CBT). Radioiodination of 2-cyano-6-hydroxybenzothiazole 2 was carried out using chloramine-T to give $^{125}I$-labeled CBT ([$^{125}I$]1) with a high radiochemical yield ($90{\pm}6%$ isolated yield, n=3) and radiochemical purity (>99%). To evaluate the radiolabeling efficiency of $^{125}I$-labeled CBT, model compounds, L-cysteine and N-terminal cysteine conjugated cRGD peptide were reacted with [$^{125}I$]1 under mild conditions. The radiolabeling reactions rapidly provided the $^{125}I$-labeled products [$^{125}I$]5 and [$^{125}I$]6 with excellent radiochemical yields and radiochemical purity. Therefore, we demonstrate that [$^{125}I$]1 will be a useful prosthetic group for radioactive iodine labeling of N-terminal cysteine bearing biomolecules.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.3 no.2
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• pp.98-102
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• 2017

We demonstrate a detail protocol for the radiosynthesis of a $^{125}I-labeled$ tetrazine prosthetic group and its application to the efficient radiolabeling of trans-cyclooctene-group conjugated human serum albumin (3) using inverse-electron-demand Diels-Alder reaction. Radioiodination of the stannylated precursor (2) was carried out by using [$^{125}I$]NaI and chloramine T as an oxidant at room temperature for 15 min. After HPLC purification of the crude product, the purified $^{125}I-labeled$ azide ([$^{125}I$]1) was obtained with high radiochemical yield ($65{\pm}8%$, n = 5) and excellent radiochemical purity (>99%). Inverse-electron-demand Diels-Alder reaction between ([$^{125}I$]1) and 3 gave the $^{125}I-labeled$ human serum albumin ([$^{125}I$]4) with more than 99% of radiochemical yield as determined by radio-thin-layer chromatography (radio-TLC). These results clearly indicate that the present radiolabeling method will be useful for the efficient and convenient radiolabeling of trans-cyclooctene-group containing biomolecules.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.4 no.2
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• pp.85-89
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• 2018

We demonstrate a detail protocol for the radiosynthesis of an $^{125}I$-labeled MSTP prosthetic group and its application to the efficient radiolabeling of human serum albumin (HSA). Radioiodination of the precursor (2) was carried out by using $[^{125}I]$NaI and chloramine T as an oxidant at room temperature for 15 min. After HPLC purification of the crude product, the purified $^{125}I$-labeled MSTP ($[^{125}I]1$) was obtained with high radiochemical yield ($73{\pm}5%$, n = 3) and excellent radiochemical purity (>99%). Site-specific reaction between ($[^{125}I]1$) and HSA gave the $^{125}I$-labeled human serum albumin ($[^{125}I]3$) with more than 99% of radiochemical yield as determined by radio-thin-layer chromatography (radio-TLC). These results clearly demonstrate that the present radiolabeling method will be useful for the efficient and convenient radiolabeling of thiol-bearing biomolecules.

• Journal of the Korean Chemical Society
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• v.9 no.2
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• pp.96-100
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• 1965

Possibility on carrier-free Fe-59 preparation by Korean TRIGA Mark Ⅱ reactor was investigated, namely average cross section on $Co^{59}$(n,p) $Fe^{59}$ reaction, separation by anion exchange resin and radiochemical purity. Radiochemical purity of Fe-59 separated was checked by the method of ${\gamma}$-ray spectrometry with 256-multichannel pulse height analyzer and of half life determination. This method permits Fe-59 preparation with radiochemical purity of > 99.9%.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.5 no.2
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• pp.83-88
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• 2019

In order to understand the in vivo biodistribution of repebody protein (RB), an efficient and simple radiolabeling method for the protein is needed. We demonstrate a detailed protocol for the radiosynthesis of an ¹¹¹In radiolabeled tetrazine prosthetic group and its application to the efficient radiolabeling of trans-cyclooctene-group conjugated repebody protein using inverse-electron-demand Diels-Alder reaction. First, 1,2,4,5-tetrazine (Tz) conjugated with a DOTA chelator, was used for preparing the radiolabeled DOTA complex with ¹¹¹In. Second, the trans-cyclooctene (TCO) functionalized repebody protein was synthesized which allows for the preparation of radiolabeled proteins by copper-free click chemistry. Following incubation with the ¹¹¹In-radiolabeled DOTA complex (¹¹¹In-Tz), the TCO-functionalized RB (TCO-RB) was radiolabeled successfully with ¹¹¹In, with a high radiochemical yield (69.5%) and radiochemical purity (>99%). The radiolabeling of repebody protein by copper-free click chemistry was accomplished within 20 min, with great efficiency in aqueous conditions. These results clearly indicate that the present radiolabeling method will be useful for the efficient and convenient radiolabeling of trans-cyclooctene-group containing biomolecules.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.3 no.1
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• pp.15-17
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• 2017

In carbon-11 labeling, $[^{11}C]$methyltriflate (methyltrifluoromethanesulfonate, MeOTf) is the most widely used through mild reaction condition with high yield. Strong inorganic bases, KOH, NaH and so on, were chosen to activate precursors that have phenolic alcohol as a nucleophilic moiety, because of its poor nucleophilicity. However, these catalyst can also react with radioactive intermediate, $[^{11}C]$MeOTf to afford side products. We will briefly discuss the history of the effort to increase the yield of $[^{11}C]$raclopride and suggest the alternate method for better radiochemical yield and consistency.

• The Korean Journal of Nuclear Medicine
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• v.23 no.1
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• pp.63-69
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• 1989

In order to develop technetium-99m-labelled human albumin microsphere (HAM) for lung scintigraphy, various experimemts such as preparation and fractionation of HAM, establishment of optimal labelling conditions, determination of radiochemical purity, stability test and biodistribution of $^{99m}Tc-HAM$ were carried out. HAM was prepared from the suspension of 1ml aqueous human serum albumin (25%) in 130 ml of olive oil at $130\sim135^{\circ}$ with vigorous stirring. The resulting HAM was fractionated with microsieve to get the desired particle size $(15\sim50\mu)$ and autoclaved for sterilizaiton. The HAM particles were treated with stannous chloride and the pH of the suspension was adjusted to $3.0\sim3.5$ with phosphate buffer. After freeze-drying the contents of single reaction vial containing 5 mg of HAM and 0.2 mg of $SnCl_2$ it was reacted with $Na^{99m}TcO_4$. The labelling yield was higher than 99.5% and the stability of $^{99m}Tc-HAM$ was high enough to maintain 99.1% of radiochemical purity up to 24 hours. Lung and liver uptake in mice was found to be 94% and 0.9%, respectively. Excellent rabbit and human lung scans were also obtained.

• Journal of the Korean Chemical Society
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• v.11 no.2
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• pp.51-55
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• 1967

A procedure, which is effective enough to label various compounds at low temperature by radioactive iodine, was investigated. The chloramine-T procedure was mostly effective for labelling various protein, amino acids, hormones, and organic compounds by iodine, and the procedure was able to afford both high specific activity and high radiochemical yield. However, the procedure was ineffective for labelling unsaturated compounds or other organic compounds which has not active aromatic nucleus of reactive character. The radiochemical yield of the procedure was generally averaged from 100% to 60%. The reactivity of the aromatic part of the organic compound towards this reagent was correspond to that of an electrophillic reagent. The procedures were described and the reaction path was considered.