*2.2. Radiochemistry of 68Ga-Nitroimidazole*

The synthesis of 68Ga-Nitroimidazole was performed as previously described [21]. Briefly, we obtained 68Ga from our inhouse 68Ge/68Ga generator (iThemba LABS, Somerset West, South Africa). We received the Nitroimidazole peptide complexed with TRAP chelator from Korea (Radiation Applied Life Sciences, Department of Nuclear Medicine and Cancer Research Institute of Radiation Medicine, Seoul National University College of Medicine, Seoul, Korea). This nitroimidazole residue, 2-(2-nitroimidazolyl)ethylamine was conjugated with TRAP via an acid-amine coupling reaction in dimethylsulfoxide (DMSO) using 2-(1*H*-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate (HBTU) as a coupling agent in the presence of *N*,*N*-diisopropylethylamine (DIPEA) as a base. Radiolabeling was conducted at pH of 4.5 at 95 ◦C in a heating block for 10 min. Labelling efficiency was verified by instant thin layer chromatography (ITLC) using 0.1 M Na2CO3. Radiochemical yields of the prepared derivatives were found to be >96% for all the derivatives.
