Keywords: PET, copper, Cu, imaging, nanoparticle
Summary:Nanoparticles (NP) are promising contrast agents for positron emission tomography (PET) radionuclide imaging that can increase signal intensity by localizing clusters of PET radionuclides together. However, methods to load NPs with PET radio-nuclides suffer from harsh loading conditions, poor loading efficacies, or result in NP surface modifications that alter targeting abilities during in vivo imaging. We present the formation of water dispersible and polyethylene coated (PEG) NPs that encapsulate phthalocyanines into NP cores at greater 50% total NP weight, using the self-assembly technique Flash NanoPrecipitation. Phthalocyanine NPs rapidly and spontaneously chelate metals under mild conditions, and can act as sinks for PET radionuclides such as 64-Cu to produce PET-active NPs. NPs chelate copper(II) with characteristic rates of 1,845 M-1 hr-1 at pH6 and 37ºC conditions, which translates to >90% radionuclide chelation within one hour. NP physical properties, such as core composition, core fluidity, and size can be tuned to modulate chelation kinetics. These NPs retain 64Cu even in the presence of the strong chelator, ethylenediaminetetraacetic acid. The development of these constructs for rapid and facile radio-nuclide labeling expands the applications of NP-based PET imaging.