title: Promising bifunctional chelators for copper 64-PET imaging: practical (64)Cu radiolabeling and high in vitro and in vivo complex stability.
abstract: Positron emission tomography (PET) using copper-64 is a sensitive and non-invasive imaging technique for diagnosis and staging of cancer. A bifunctional chelator that can present rapid radiolabeling kinetics and high complex stability with (64)Cu is a critical component for targeted PET imaging. Bifunctional chelates 3p-C-NE3TA, 3p-C-NOTA, and 3p-C-DE4TA were evaluated for complexation kinetics and stability with (64)Cu in vitro and in vivo. Hexadentate 3p-C-NOTA and heptadentate 3p-C-NE3TA possess a smaller TACN-based macrocyclic backbone, while nonadentate 3p-C-DE4TA is constructed on a larger CYCLEN-based ring. The frequently explored chelates of (64)Cu, octadentate C-DOTA and hexadentate C-NOTA were also comparatively evaluated. Radiolabeling kinetics of bifunctional chelators with (64)Cu was assessed under mild conditions. All bifunctional chelates instantly bound to (64)Cu in excellent radiolabeling efficiency at room temperature. C-DOTA was less efficient in binding (64)Cu than all other chelates. All (64)Cu-radiolabeled bifunctional chelates remained stable in human serum without any loss of (64)Cu for 2 days. When challenged by an excess amount of EDTA, (64)Cu complexes of C-NOTA, 3p-C-NE3TA and 3p-C-NOTA were shown to be more stable than (64)Cu-C-DOTA and (64)Cu-3p-C-DE4TA. (64)Cu complexes of the new chelates 3p-C-NE3TA and 3p-C-NOTA displayed comparable in vitro and in vivo complex stability to (64)Cu-C-NOTA. In vivo biodistribution result indicates that the (64)Cu-radiolabeled complexes of 3p-C-NOTA and 3p-C-NE3TA possess excellent in vivo complex stability, while (64)Cu-3p-C-DE4TA was dissociated as evidenced by high renal and liver retention in mice. The results of in vitro and in vivo studies suggest that the bifunctional chelates 3p-C-NE3TA and 3p-C-NOTA offer excellent chelation chemistry with (64)Cu for potential PET imaging applications.
authors.affiliation: Department of Chemistry, Illinois Institute of Technology, 3101 S. Dearborn St, LS 182, Chicago, IL, 60616, USA.
authors.forename: Ningjie
authors.initials: N
authors.lastname: Wu
authors.affiliation: Department of Chemistry, Illinois Institute of Technology, 3101 S. Dearborn St, LS 182, Chicago, IL, 60616, USA.
authors.forename: Chi Soo
authors.initials: CS
authors.lastname: Kang
authors.affiliation: Department of Chemistry, Illinois Institute of Technology, 3101 S. Dearborn St, LS 182, Chicago, IL, 60616, USA.
authors.forename: Inseok
authors.initials: I
authors.lastname: Sin
authors.affiliation: Department of Chemistry, Illinois Institute of Technology, 3101 S. Dearborn St, LS 182, Chicago, IL, 60616, USA.
authors.forename: Siyuan
authors.initials: S
authors.lastname: Ren
authors.affiliation: Department of Veterinary Medicine and Surgery, University of Missouri, Columbia, MO, USA.
authors.forename: Dijie
authors.initials: D
authors.lastname: Liu
authors.affiliation: Department of Veterinary Medicine and Surgery, University of Missouri, Columbia, MO, USA.
authors.forename: Varyanna C
authors.initials: VC
authors.lastname: Ruthengael
authors.affiliation: Research Service, Harry S. Truman Memorial Veterans' Hospital, University of Missouri, Columbia, USA.|Department of Veterinary Medicine and Surgery, University of Missouri, Columbia, MO, USA.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Lewis
authors.affiliation: Department of Chemistry, Illinois Institute of Technology, 3101 S. Dearborn St, LS 182, Chicago, IL, 60616, USA. chong@iit.edu.
authors.forename: Hyun-Soon
authors.initials: HS
authors.lastname: Chong
mesh_terms: D000818:Animals; D002614:Chelating Agents / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D003301:Copper Radioisotopes / Q000737:chemistry*; D066298:In Vitro Techniques; D007700:Kinetics; D051379:Mice; D049268:Positron-Emission Tomography / Q000379:methods*
chemical_list: D002614:Chelating Agents; D003301:Copper Radioisotopes
keywords: Bifunctional chelator; Cu-64; Pet imaging