[Preparation and quality control of 99mTc labeled MDR1 oligonucleotide DNAs]

The aim of this study is to explore the optimal labeling condition of technetium-99m labeled antisense oligonucleotides (ASON) DNA and sense oligonueleotides (SON) DNA against multi-drug resistance gene-1 (MIDR1) mRNA, to prepare its two-step icefrozen kits, and to perform the quality control of technetium-99m labeled ASON and SON DNAs and its two-step icefrozen kits. A 20 mer single-stranded ASON sequence and its SON sequence against MDR1 mRNA were synthesized respectively, both of the ASON and SON DNAs were uniform phosphorothioated for this investigation with a primary amine on the 5'-end via a six-carbon alkyl linker, and then were labeled with technetium-99m by conjugating with the bifunctional chelator S-Acetyl NHS-MAG3 to form ASON- and SON-MAC3 DNAs. The optimal labeling condition was explored by varying the amount of ASON- and SON-MAG3 DNAs, SnCl2.2H2O and buffer, the pH value in the reaction medium was also adjusted. The technetium-99m labeled ASON and SON DNAs' two-step icefrozen kits were developed. The radiochemical purities, labeling stability of ASON- and SON-MAG3 DNAs in vivo and vitro were measured, and stability of the two-step icefrozen kits were also studied. The recycled rates of ASON- and SON-MAG3 DNAs were over 70% (n >6), the two-step icefrozen kits of ASON- and SON-MAG3 DNAs were colourless ice crystal. The radiochemical purities of technetium-99m labeled ASON- and SON-MAG3 DNAs were over 92 %. The radiochemical purities were over 90% after stored at room temperature for 24 hours. The kits were stable within 6 months when stored at 0 degrees C, the radiochemical purities of technetium-99m labeled ASON- and SON-MAG3 DNAs were still over 90%. The two-step icefrozen kits of ASON- and SON-MAG3 DNAs were successfully developed. The radiochemical purities were all over 90%. The labeling method was simple, feasible and efficient with good stability.