Abstract
Zirconium-89 (89Zr, t1/2 = 3.27 days) owns great potential in nuclear medicine, being extensively used in the labelling of antibodies and nanoparticules. 89Zr can be produced by cyclotron via an 89Y(p,n)89Zr reaction while using an 89Y-foil target. In this study, we investigated for the first time the use of 89Y-pressed target for the preparation of 89Zr-oxalate via a (p,n) reaction. We performed comparative studies with an 89Y-foil target mounted on custom-made target supports. A new automated cassette-based purification module was used to facilitate the purification and the fractionation of 89Zr-oxalate. The effective molar activity (EMA) was calculated for both approaches via titration with deferoxamine (DFO). The radionuclidic purity was determined by gamma-ray spectroscopy and the metal impurities were quantified by ICP-MS on the resulting 89Zr-oxalate solution. The cassette-based purification process leading to fractionation is simple, efficient, and provides very high EMA of 89Zr-oxalate. The total recovered activity was 81 ± 4% for both approaches. The highest EMA was found at 13.3 MeV and 25 μA for 0.25-mm thick 89Y-foil. Similar and optimal production yields were obtained at 15 MeV and 40 μA while using 0.50-mm thick 89Y-foil and pressed targets. Metallic impurities concentration was below the general limit of 10 ppm for heavy metals in the US and Ph.Eur for both 89Y-foil and pressed targets. Overall, these results show that the irradiation of 89Y-pressed targets is a very effective process, offering an alternative method for 89Zr production.
Highlights
Introduction89 Zr-based imaging presents numerous advantages, including a sufficiently high abundance of β+ emission with low maximum energy (Emax (β+ ) = 897 keV and Eave
Zirconium-89 (89 Zr, t1/2 = 78.4 h) decays via both β+ emission (22.7%) and electron capture (73.3%) to an intermediate 89m Y state (t1/2 = 15.7 s), which decays to stable 89 Y via a γ-ray emission of 909 keV
The long half-life of this radionuclide is well suited for the design of radiotracers, such as nanoparticules and monoclonal antibodies, which require extended in vivo circulation times for optimal biodistribution and tumour targeting [1,2,3]
Summary
89 Zr-based imaging presents numerous advantages, including a sufficiently high abundance of β+ emission with low maximum energy (Emax (β+ ) = 897 keV and Eave. (β+ ) = 396.9 keV), resulting in a good spatial resolution for mAb-tracking by PET imaging [4,5,6]. The most widespread application for 89 Zr has been the development of immuno-PET tracers based on mAb for in vivo PET cancer imaging. Sci. 2018, 8, 1579 improve staging, provide an effective method to detect recurrence, and allow for the identification of patients who will be eligible for more personalized and adapted treatment to their specific cancer in order to improve their quality of life.
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