Facile synthesis of ⁶⁴Cu-doped Au nanocages for positron emission tomography imaging

This article reports a simple and reliable approach to the synthesis of Cu-doped Au nanocages through the codeposition of Au and Cu on the surfaces (both outer and inner) of pre-synthesized Au nanocages by reducing HAuCl₄ and CuCl₂ with ascorbic acid under alkaline conditions. By controlling the total amount of Au and Cu deposited and/or the molar ratio between these two metals, we were able to adjust the Cu content in the resultant Au nanocages. The localized surface plasmon resonance properties of the Cudoped Au nanocages resemble those of the conventional Au nanocages, with strong and tunable absorption in the nearinfrared region. When radioactive ⁶⁴CuCl₂ was used in combination with nonradioactive CuCl₂ as a source to elemental Cu, we obtained ⁶⁴Cu-doped Au nanocages. The radioactive nanocages could serve as tracers for position emission tomography (PET) imaging, and they were found to accumulate effectively in both 4T1 and patient derived xenograft (PDX) tumor models due to the enhanced permeability and retention effect. Autoradiography analysis indicated a homogeneous intra-tumoral distribution for these nanocages. Taken together, the ⁶⁴Cu-doped Au nanocages are promising for image-guided cancer theranostics.