Radiochemistry
In order to use certain radioactive elements, there is sometimes a need to first find a way to change its oxidation status and work out which chelators enable stable binding of the element and to then test which chelator/radiopharmaceutical shows the best stability, i.e. keeps the radioactive in its place the longest.
Example 1. Thallium-201 attached to pypa-PSMA to target PSMA-positive prostate cancer tumours
We created a PSMA-targeting radiopharmaceutical using the chelator pypa and radionuclide thallium-201. Here we can see it localising to the tumour (T) and being excreted mostly through the kidneys and the bladder. From Rigby et al. 2022.
Example 2. Thallium-201 stability when chelated with EDTA, DTPA or DOTA
On the left, we can see a graph depicting the stability in blood/serum (or lack thereof) for thallium-201 oxidised to a 3+ oxidation state when chelated with EDTA, DTPA, and DOTA. Thallium-201 chelated with DOTA appears very stable in ammonium acetate (the buffer in which the chelation is achieved) and is more stable in cell medium and serum than when chelated with EDTA and DTPA. This suggests that out of the three chelators, DOTA would be preferential for future cancer-targeting radiopharmaceutical development. From Rigby et al. 2021.