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KMID : 1148920090430040330
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Nuclear Medicine and Molecular Imaging
2009 Volume.43 No. 4 p.330 ~ p.336
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Radiolabeling of NOTA and DOTA with Positron Emitting 68Ga and Investigation of In Vitro Properties
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Jeong Jae-Min
Lee Yoon-Sang
Lee Dong-Soo
Chung June-Key
Lee Myung-Chul
Kim Young-Ju
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Abstract
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Purpose: We established radiolabeling conditions of NOTA and DOTA with a generator-produced PET radionuclide 68Ga and studied in vitro characteristics such as stability, serum protein binding, octanol/water distribution, and interference with other metal ions.
Materials and Methods: Various concentrations of NOTA?3HCl and DOTA?4HCl were labeled with 1 mL 68GaCl3 (0.18～5.75 mCi in 0.1 M HCl) in various pH. NOTA?3HCl (0.373 mM) was labeled with 68GaCl3 (0.183～0.232 mCi/0.1 M HCl 1.0 mL) in the presense of CuCl2, FeCl2, InCl3, FeCl3, GaCl3, MgCl2 or CaCl2 (0～6.07 mM) at room temperature. The labeling efficiencies of 68Ga-NOTA and 68Ga-DOTA were checked by ITLC-SG using acetone or saline as mobile phase. Stabilities, protein bindings, and octanol distribution coefficients of the labeled compounds also were investigated.
Results: 68Ga-NOTA and 68Ga-DOTA were labeled optimally at pH 6.5 and pH 3.5, respectively, and the chelates were stable for 4 hr either in the reaction mixture at room temperature or in the human serum at 37°C. NOTA was labeled at room temperature while DOTA required heating for labeling. 68Ga-NOTA labeling efficiency was reduced by CuCl2, FeCl2, InCl2, FeCl3 or GaCl3, however, was not influenced by MgCl2 or CaCl2. The protein binding was low (2.04~3.32%). Log P value of 68Ga-NOTA was -3.07 indicating high hydrophilicity.
Conclusion: We found that NOTA is a better bifunctional chelating agent than DOTA for 68Ga labeling. Although, 68Ga-NOTA labeling is interfered by various metal ions, it shows high stability and low serum protein binding.
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KEYWORD
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Ga-68, gallium, protein binding, bifunctional chelating agent, generator, NOTA, DOTA
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