Bn2DT3A, a Chelator for 68Ga Positron Emission Tomography: Hydroxide Coordination Increases Biological Stability of [68Ga][Ga(Bn2DT3A)(OH)]−

Price, Thomas W.; Renard, Isaline; Prior, Timothy J.; Kubíček, Vojtěch; Benoit, David M.; Archibald, Stephen J.; Seymour, Anne Marie; Hermann, Petr; Stasiuk, Graeme J.

Abstract

The chelator Bn2DT3A was used to produce a novel 68Ga complex for positron emission tomography (PET). Unusually, this system is stabilized by a coordinated hydroxide in aqueous solutions above pH 5, which confers sufficient stability for it to be used for PET. Bn2DT3A complexes Ga3+ in a hexadentate manner, forming a mer-mer complex with log K([Ga(Bn2DT3A)]) = 18.25. Above pH 5, the hydroxide ion coordinates the Ga3+ ion following dissociation of a coordinated amine. Bn2DT3A radiolabeling displayed a pH-dependent speciation, with [68Ga][Ga(Bn2DT3A)(OH)]- being formed above pH 5 and efficiently radiolabeled at pH 7.4. Surprisingly, [68Ga][Ga(Bn2DT3A)(OH)]- was found to show an increased stability in vitro (for over 2 h in fetal bovine serum) compared to [68Ga][Ga(Bn2DT3A)]. The biodistribution of [68Ga][Ga(Bn2DT3A)(OH)]- in healthy rats showed rapid clearance and excretion via the kidneys, with no uptake seen in the lungs or bones.

Citation

Price, T. W., Renard, I., Prior, T. J., Kubíček, V., Benoit, D. M., Archibald, S. J., …Stasiuk, G. J. (2022). Bn2DT3A, a Chelator for 68Ga Positron Emission Tomography: Hydroxide Coordination Increases Biological Stability of [68Ga][Ga(Bn2DT3A)(OH)]−. Inorganic chemistry, 61(43), 17059–17067. https://doi.org/10.1021/acs.inorgchem.2c01992

• Journal Article Type: Article
• Acceptance Date: Oct 14, 2022
• Online Publication Date: Oct 17, 2022
• Publication Date: Oct 31, 2022
• Deposit Date: Sep 11, 2023
• Publicly Available Date: Sep 12, 2023
• Journal: Inorganic Chemistry
• Print ISSN: 0020-1669
• Electronic ISSN: 1520-510X
• Publisher: American Chemical Society
• Peer Reviewed: Peer Reviewed
• Volume: 61
• Issue: 43
• Pages: 17059–17067
• DOI: https://doi.org/10.1021/acs.inorgchem.2c01992
• Keywords: Anions; Ligands; Mechanisms of action; Radiolabeling; Reaction mechanisms
• Public URL: https://hull-repository.worktribe.com/output/4112016