Implementation of a new separation method to produce qualitatively improved ⁶⁴Cu

Abstract

Background 64Cu (T1/2 = 12.7 h) is an important radionuclide for diagnostic purposes and used for positron emission tomography (PET). A previous method utilized at Paul Scherrer Institute (PSI) proved to be unreliable and, while a method using anion exchange chromatography is a popular choice worldwide, it was felt a different approach was required to obtain a robust chemical separation method. Methods Enriched 64Ni targets were created by electroplating on gold foil. The targets were irradiated with protons degraded to approximately 11 MeV at PSI's Injector 2 72 MeV research cyclotron and subsequently dissolved in HCl. The resultant solution was loaded onto AG MP‐50 cation exchange resin and the 64Cu separated from its target material and radiocobalt impurities, produced as part of the irradiation process, using various specific mixtures of HCl/acetone solution. The eluted product was evaporated and picked up in dilute HCl (0.05 M). The chemical purity of 64Cu was determined by radiolabeling experiments at the highest possible molar activities. Results Reproducible results were obtained, yielding 3.6 to 8.3 GBq 64Cu of high radionuclidic and radiochemical purity. The product was labeled to NODAGA‐RGD, achieved at up to 500 MBq/nmol, indicating the high chemical purity. In a proof‐of‐concept in vivo study, 64Cu‐NODAGA‐RGD was used for PET imaging of a tumor‐bearing mouse. Conclusion The chemical separation devised to produce high‐quality 64Cu proved to be robust and reproducible. The concept can be used at medical cyclotrons utilizing a solid target station, such that 64Cu can be used at hospitals for PET imaging.

In Vivo Imaging of Local Inflammation: Monitoring LPS-Induced CD80/CD86 Upregulation by PET

“…We did not find information on whether the mutations which reduce binding to human Fc receptors have the same effect on the binding to murine Fc receptors [10]. The unmodified human IgG1 Fc part would have a weaker affinity to the murine than human Fc receptors [28]. The above mentioned optimised CD80-targeting smaller proteins lack the Fc part.…”

“…The produced conjugate (NODAGA-abatacept) was purified by 7 ultracentrifugation steps with Ultra Centrifugal Filter Units (Amicon, 15 ml, 30 kDa cutoff) according to the protocol [27]. The chelator/protein ratio of the product was quantified by deglycosylation with Protein Deglycosylation Mix P6039 (New England Biolabs, Ipswich, MA, USA), reduction with DTT and fragment analysis with LC-MS. Copper-64 was produced via the 64 Ni(p,n) 64 Cu nuclear reaction at the Injector II cyclotron facility at the Center for Radiopharmaceutical Sciences, Paul Scherrer Institute (CRS, PSI, Villigen, Switzerland) [28].…”

Electrochemical deposition of nickel from aqueous electrolytic baths prepared by dissolution of metallic powder

“…The solid Ni targets used in these processes are typically obtained through electrodeposition on a substrate with a good electronic and heat conductivity, e.g. gold [2,[16][17][18][19][20][21][22][23][25][26][27], platinum [15,28,29] or copper covered with a protective layer of Au or Ag [24,30]. Unfortunately, some of natural nickel isotopes, which act as targets in production of the medical radioisotopes, are of low natural abundance (from 0.9 to 3.6% for 61 Ni, 62 Ni and 64 Ni [31]).…”

“…Such bath usually contains from few tens to ca. 120 mg of Ni [15,18,20,22,23,26,28,32]. Work with such small amount of the electroactive species leads to serious consequences for the electroplating procedure.…”

“…at least 95%) amount of the nickel is expected to be deposited. It is a common approach to continue the target electrodeposition until the bath becomes colourless (naked eye judgement) [15,19,20,26,28,29,36,37]. This is in contrast to the industrial plating procedures which do not require complete metal deposition and which left the bath usually only weakly depleted with the metal after completing the deposition.…”