Background: Peptide-based agents are used in molecular imaging due to their unique properties, such as
rapid clearance from the circulation, high affinity and target selectivity. Many of the radiolabeled peptides have
been clinically experienced with diagnostic accuracy. The aim of this study was to investigate in vivo biological
behavior of [99mTc(CO)3(H2O)3]+ radiolabeled glycylglycine (GlyGly).
Methods: Glycylglycine was radiolabeled with a high radiolabeling yield of 94.69±2%, and quality control of the
radiolabeling process was performed by thin layer radiochromatography (TLRC) and High-Performance Liquid
Radiochromatography (HPLRC). Lipophilicity study for radiolabeled complex (99mTc(CO)3-Gly-Gly) was carried
out using solvent extraction. The in vivo evaluation was performed by both biodistribution and SPECT imaging.
Results: The high radiolabelling yield of 99mTc(CO)3-GlyGly was obtained and verified by TLRC and HPLRC as
well. According to the in vivo results, SPECT images and biodistribution data are in good accordance. The
excretion route from the body was both hepatobiliary and renal.
Conclusion: This study shows that 99mTc(CO)3-GlyGly has the potential to be used as a peptide-based imaging
agent. Further studies, 99mTc(CO)3-GlyGly can be performed on tumor-bearing animals.