Alpha radiolysis of DOTA ligand in aqueous solutions with helium ion beams

Abstract

Alpha irradiation of DOTA ligand in pure water with helium ion beam was studied.• As DOTA concentration in water increases, H2O2 formation decreases.• Whereas molecular hydrogen (H2) and carbon dioxide (CO2) formation increases.• DOTA degradation products were identified by ESI-MS.• A degradation scheme for the DOTA ligand is proposed.

Effect of metal complexation on the radiolytic stability of DOTA

“…A decrease in signal intensity is observed upon irradiation, which was also reported by Fiegel et al 36 They observed that the higher the concentration of DOTA in solution, the higher the hydrogen yields and attributed the decrease in NMR signal intensity to the degradation of DOTA through hydrogen abstraction leading to the formation of molecular hydrogen H 2 . 36 At 20 and 30 kGy, DOTA keeps degrading. This results in a decrease in intensity and an increasing shift of the NMR signals.…”

“…Our experimental results and previous work 36 show that cyclen bonds of DOTA are not subjected to radiolysis, while the acetate arms can be broken. Therefore, BDEs were calculated only for the bonds belonging to the acetate arms.…”

“…From 10 to 30 kGy, peaks corresponding to the degradation products of DOTA are observed at m / z = 347, 317 and 361. The identifications were proposed based on the work of Fiegel et al 36 The major ion at m / z = 347 corresponds to DOTA with the loss of an acetate arm –CH 2 COOH. This explains the shift of the acetate arm signals observed in the NMR spectra.…”

“…This phenomenon is not observed for H 4 DOTA because the cleavage of the C–H bond is immediately followed by the rupture of C–C bonds or N–C bonds through multiple reactions and rearrangement. 28,36…”

PyRad: A software shell for simulating radiolysis with Qball package

“…are being studied as a promising cure for cancer 3–6 . Despite the different fields of application both of these areas are connected by the chemistry of aqueous solutions under irradiation 7–11 . Experimental methods require special laboratory conditions with the use of sources of ionizing radiation (accelerators, gamma‐chambers, and nuclear reactors).…”