Preparation of ^<99m>Tc radiopharmaceuticals using macroreticular Sn (II) complex

氯化亚锡（SnCl_2）具有易水解、易氧化的缺点，但在制备~ 1 Tc放射性药物时，大多数商品化试剂盒都含有SnCl_2作为合适的还原剂<99m>。本文提出用不溶性大分子Sn（II）（R-Sn）配合物代替SnCl_2，以解决SnCl_2过量所带来的问题。其中，含有氨基膦酸基团的螯合树脂表现出高容量的Sn（II），这强烈结合到树脂的螯合。预期使用R-Sn络合物可最大程度地减少Sn（II）对1 <99m>Tc标记溶液的污染，并可有效地用作还原剂，用于1 <99m>Tc标记含有巯基的蛋白质。因此，将R-Sn配合物用于<99m>人免疫球蛋白（IgG）的直接~ 1 Tc标记，以最小化Sn（II）的影响。简单<99m>地通过在pH 7溶液中短期混合每个IgG分子含有&gt;2个-SH基团的IgGa、高锝酸盐和R-Sn络合物，以大于90%的产率实现13 Tc标记<99m>。通过<99m>这种标记方法获得的13 Tc-IgGa具有高稳定性，这是基于13 Tc的巯基特异性结合<99m>，而不从另一种弱结合的13 <99m>Tc-复合物转移螯合。

Stannous chloride (SnCl_2) has the disadvantages of being easily hydrolyzed and oxidized, but it is included in most commercial kits as an appropriate reducing agent in the preparation of ^<99m>Tc radiopharmaceuticals. The replacement of SnCl_2 by the insoluble macromolecular Sn (II) (R-Sn) complex was proposed as a way to resolve some of the problems caused by a large excess of SnCl_2 Macroreticular chelating ion exchange resins having an adsorption ability for Sn (II) were investigated for the development of R-Sn complex. Among them, a chelating resin containing aminophosphonic acid groups showed a high capacity for Sn (II) , which bound strongly to the resin by chelation. The use of the R-Sn complex was expected to minimize Sn (II) comtamination of the ^<99m>Tc labeling solution and be effectively used as a reducing agent for ^<99m>Tc labeling of proteins containing sulfhydryl groups. So, the R-Sn complex was applied to the direct ^<99m>Tc labeling of human immunoglobulin (IgG) to minimize the influence of Sn (II). ^<99m>Tc labeling was achieved at greater than 90% yield simply by the short-term mixing of IgGa containing>2 -SH groups per IgG molecule, ^<99m>Tc pertechnetate, and the R-Sn complex in pH 7 solution. The ^<99m>Tc-IgGa obtained by this labeling method has high stability based on the thiol-specific binding of ^<99m>Tc without transchelation from another weakly bound ^<99m>Tc-complex.