Characterization of insoluble macromolecular Sn(II) complex and its application to the 99mTc labeling of human serum albumin-bearing Mercapto groups

Abstract A chelating ion exchange resin containing aminophosphonic acid groups was used as a polymer matrix for the preparation of an insoluble macromolecular Sn(II)(R-Sn) complex. Sn(II), which strongly bound to the surface of the polymer matrix by chelation, retained the ability to reduce 99m Tc in the R-Sn complex. Human serum albumin-bearing-mercapto groups (HMA) was labeled with 99m Tc at pH 2–3 using the R-Sn complex or SnCl 2 as reducing agent. The 99m Tc-HMA labeled with the R-Sn complex resulted in a higher sustained level of radioactivity in the blood of mice than the 99m Tc-HMA labeled with SnCl 2 . These results suggest that the use of the R-Sn complex minimized Sn(II) contamination of the 99m Tc labeling solution and can be used effectively as a reducing agent for 99m Tc labeling of proteins containing sulfhydryl groups.