Biodistribution of 64Cu-Labeled AuNCs in Mice

All animal studies were performed in compliance with guidelines set forth by the NIH Office of Laboratory Animal Welfare and approved by the Washington University Animal Studies Committee. Biodistribution studies were performed in male C57BL/6 mice weighing 20 to 25 g (n = 4, Charles River Laboratory, Wilmington, Massachusetts) with 0.37 MBq (0.057 pmol) of ⁶⁴Cu-AuNCs-PEG-MSH or ⁶⁴Cu-AuNCs-PEG in 100 μL of saline (APP Pharmaceuticals, Schaumburg, Illinios) injected via the tail vein. The mice were anesthetized with inhaled isoflurane during tracer injection and reanesthetized before euthanasia by cervical dislocation at each time point. Organs of interest were collected, weighed, and counted with a Beckman 8000 gamma counter (Beckman, Brea, California). Standards were prepared and measured along with the samples to calculate the percentage of the injected dose per gram of tissue (%ID/g).^{10 (link),22 (link)}