Design of a multivalent bifunctional chelator for diagnostic 64Cu PET imaging in Alzheimer’s disease

Metal radiotracers exhibit beneficial properties that can improve in vivo positron emission tomography (PET) imaging over traditional radionuclides, such as longer half-lives, facile last-stage radiolabeling steps, and the potential for dual imaging-therapy applications. Among such radionuclides, 64Cu exhibits a longer half-life (t1/2 = 12.7 h) that allows for later PET imaging times and the ability to distribute 64Cu imaging agents to facilities that do not have an on-site cyclotron. Herein, we report a 64Cu PET imaging agent that shows appreciable in vivo brain uptake and exhibits high specific affinity for beta-amyloid aggregates, leading to the successful PET imaging of amyloid plaques in the brains of 5xFAD mice versus those of wild-type mice.Herein, we report a 64Cu positron emission tomography (PET) imaging agent that shows appreciable in vivo brain uptake and exhibits high specific affinity for beta-amyloid (Aβ) aggregates, leading to the successful PET imaging of amyloid plaques in the brains of 5xFAD mice versus those of wild-type mice. The employed approach uses a bifunctional chelator with two Aβ-interacting fragments that dramatically improves the Aβ-binding affinity and lipophilicity for favorable bloodtextendashbrain barrier penetration, while the use of optimized-length spacers between the Cu-chelating group and the Aβ-interacting fragments further improves the in vivo Aβ-binding specificity and brain uptake of the corresponding 64Cu PET imaging agent.