Radiochemistry

Radiochemistry is a discipline that deals with the chemistry of radioactive materials which is different from normal chemistry as it deals with μg and ng levels of radioactive material. Radiochemicals are the source (raw) material for radiopharmaceuticals which are pharmaceuticals administered at low chemical levels where the active compound is a radioisotope which either gives off radiation that is useful for imaging or therapy. Tc-99m is the radioisotope that is used most often in radiopharmaceuticals for nuclear medicine procedures. The radiochemical that produces 99mTc, a SPECT (Single Photon Emission Computerised Tomography) imaging radioisotope, through decay is 99Mo.

The process to extract this from the fission products of U-235 was developed locally. This process now supplies 15% of the world demand. Out of the same stream I-131 is extracted, also for export. Both now performed on routine basis for commercial exploitation by NTP Radioisotope SOC. In the research arena there is a move away from SPECT towards PET (Positron Emission Tomography) due to its higher resolution. The most used PET isotope Is 18F which is produced at the Necsa site on a daily basis. An exiting PET new isotope is 68Ga which is available from a 68Ge generator also produced locally at iThemba LABS. Current focus of R&D is on radiopharmaceuticals with recent lab infrastructure upgrades and skilled personnel enabling clinical trials in humans. The high signal to mass ratio of radiochemicals also makes then ideal tracers to evaluate the biodistribution of compounds of importance in biosciences which is the other side of the radiochemical coin.

• Part of all-on-one-site nuclear infrastructure at Pelindaba; from SAFARI-1 reactor to waste disposal.
• Radiotracer Laboratory – isotope production development equipped with an HPLC-MS with various other detectors (incl. radioactive) as well as a small hot cell.
• Beta Laboratory – converted to the national preclinical imaging facility with microPET, microSPECT and optical imaging.
• Labelling Laboratory – synthesis of radiolabelled compounds for health projects in assistance of academic institutions as well as PET tracers under sterile conditions (clean room). Fully equipped with i.a. an automatic synthesis unit and HPLC with radio detectors.
• General chemical laboratories – fully equipped to carry out non-radioactive preliminary R&D.  

• Radiopharmaceuticals –development focused on oncology  (companion diagnostics) and infection and inflammation imaging; Tc, Re, Sn and lanthanide chemistry; computer modelling ofin vivo behaviour; access to animal models (rats, dogs, monkeys) through collaborative network.
• Tracers- Provision of radiotracers for in vitro and in vivobiological imaging as well as non-medical tracers for agricultural research.
• Isotope production – technology development and support for all Necsa’s bulk isotope production products – Mo-99, I-131, Lu-177, Sm-53.
• Specialised compounds – C-14 and Ca-45 labelled compounds as tracers to evaluate natural product biodistribution.
• Regulatory aspects – extensive experience in writing of licences, drug master files, quality and validation reports.

• Radiochemistry and radiopharmacy are considered scarce skills as the training/specialisation into this area is a 5 year process. Therefore the combination of an MSc and PhD is an ideal training mechanism. The Radiochemistry department therefore host MSc and PhD students in collaboration with University of Pretoria and North West University (NWU). This has been very fruitful and ~ 20 students have received their degrees or are close to completion.
• The NRF’s Professional Development Program is an excellent funding vehicle and has also allowed for appointment of the Postdocs following their PhD’s to gain work experience in these disciplines. So far 2 of the students coming from these programmes have been placed as permanent staff members.
• As the discipline of radiochemistry is not formally taught at any SA university the department reaches out by supplying lecturing capacity to the Centre for Applied Radiation and Sciences (CARST) at the NWU, Mafikeng campus.

• In collaboration with the Nuclear Medicine department of University of Pretoria / Steve Biko Academic Hospital the development of the world’s first >68 Ga infection imaging radiopharmaceutical, 68 Ga-UBI.
• In collaboration with the Nuclear Medicine department of University of Pretoria / Steve Biko Academic Hospital the development of a single vial kit for 68 Ga-PSMA which is used for imaging of prostate cancer.
• The improvement of 195m Pt-cisplatinum and phase 0 evaluation thereof as companion diagnostic for ovarian patient intended to minimise their side effects while undergoing chemotherapy.
• The design of a dual targeting mode cancer therapy agent called Glucab currently being evaluated preclinically.