The impact of zirconium-89 solution formulation on the efficiency of [⁸⁹ Zr]Zr-deferoxamine synthesis

In recent years, clinical imaging with ⁸⁹ Zr-based radiopharmaceuticals has been gaining significant importance in nuclear medicine. This article provides the results of a comparative study of methods for obtaining ⁸⁹ Zr solutions using ZR, Chelex-100, and TBP resins in the form of [⁸⁹ Zr]Zr-oxalate, [⁸⁹ Zr]Zr-chloride, and [⁸⁹ Zr]Zr-citrate in terms of purification and labeling efficiency. All evaluated methods allowed us to obtain ⁸⁹ Zr with high yield (>90% in 1 ml). The chemical form of ⁸⁹ Zr has a significant influence on the radiolabeling efficiency of the deferoxamine (DFO) chelator and its derivatives. Compared with [⁸⁹ Zr]Zr-oxalate, the application of [⁸⁹ Zr]Zr-chloride and [⁸⁹ Zr]Zr-citrate solutions leads to a higher efficacy of [⁸⁹ Zr]Zr-DFO complex formation. It should be noted that the sequence of mixing of the reagents during the radiolabeling reaction and the residual concentration of oxalic acid appeared to be crucial in the case of [⁸⁹ Zr]Zr-chloride. According to the experimental data, radiolabeling of DFO and its derivatives is preferable to use more stable chemical forms of ⁸⁹ Zr, such as [⁸⁹ Zr]Zr-citrate. The concept will be applied in the further studies involving antibody-based bioconjugates.