Preparation of 99mTc(CO)3-TPPS4 and its biological behavior evaluation
Abstract
99mTc(CO)3-TPPS4 was 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 of 99mTc(CO)3-TPPS4 was radioactively analyzed by paper chromatography. Hep2 tumor cells were incubated with 99mTc(CO)3-TPPS4 complex system in the substrate and isolated from the substrate for radioactivity count. Then 99mTc(CO)3-TPPS4 complex system was intravenously injected in hepatoma-bearing mice and directly injected in tumor tissue of the mice. Mice were photographed using SPECT. Labeling yields of 99mTc(CO)3-TPPS4 were 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 of 99mTc(CO)3-TPPS4 in 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 of 99mTc(CO)3-TPPS4 in the tumor tissue. Then the differences between 99mTc(CO)3-TPPS4 and TPPS4 were analyzed by fluoroscopy and molecular structure. It was found that the paper chromatography, HepG2 tumor cell uptake and the optimized porphyrin ring conformation of 99mTc(CO)3-TPPS4 were quite different from those of TPPS4. It was indicated that 99mTc(CO)3-TPPS4 had 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 TPPS4 by 99mTc(CO)3 core.
Handbook of Porphyrin Science now available in 46 volumes
