Preparation of99mTc(CO)3-TPPS4and its biological behavior evaluation

Abstract

99mTc(CO)3-TPPS4was prepared via the precursor [99mTc(CO)3(H2O)3]+and a preliminary investigation on its stability and behavior in Hep2 tumor cells and hepatoma-bearing mice were conducted. Labeling yield and stability of99mTc(CO)3-TPPS4was radioactively analyzed by paper chromatography. Hep2 tumor cells were incubated with99mTc(CO)3-TPPS4complex system in the substrate and isolated from the substrate for radioactivity count. Then99mTc(CO)3-TPPS4complex system was intravenously injected in hepatoma-bearing mice and directly injected in tumor tissue of the mice. Mice were photographed using SPECT. Labeling yields of99mTc(CO)3-TPPS4were more than 90% at pH = 7–8, 30 min, in a boiling bath, and it was stable for at least 14 h at pH = 2–8, rt ~95 °C. The uptake of99mTc(CO)3-TPPS4in HepG2 tumor cells was only 3–4% with the maximum uptake-time of 20 min. The SPECT images of hepatoma-bearing nude mice showed no uptake or little retention of99mTc(CO)3-TPPS4in the tumor tissue. Then the differences between99mTc(CO)3-TPPS4and TPPS4were analyzed by fluoroscopy and molecular structure. It was found that the paper chromatography, HepG2 tumor cell uptake and the optimized porphyrin ring conformation of99mTc(CO)3-TPPS4were quite different from those of TPPS4. It was indicated that99mTc(CO)3-TPPS4had no uptake or little retention in hepatic tumors, unlike those biological behaviors of TPPS4. This may be due to the modification of porphyrin ring conformation of TPPS4by99mTc(CO)3core.