Tracking Copper Biodistribution in Tumor-Bearing Mice

BALB/c mice bearing EMT6 tumors in the right flank, with tumor sizes of 4–6 mm at day 0, were divided into three groups (n = 5). Mice in groups 1 and 2 were intratumorally injected with HCuSNPs-CpG (1 mg of Cu per mouse). Mice in group 1 were treated with laser (900 nm, 2.0 W/cm², 40 s) at 30 min after injection and at day 6. Mice in group 3 without injection were used as control for endogenous Cu. All mice were transferred to mouse metabolic cages (Tecniplast) for urine and feces collection up to 14 days. At day 14, all mice were euthanized. The heart, liver, spleen, lung, kidney, tumor, and tumor-draining lymph nodes were collected. Tissue, urine, and feces samples were digested for the inductively coupled plasma mass spectrometer (ICP-MS) (model: X7, Thermo Electron Corporation) quantitative analysis of Cu according to our previously reported procedure.^{36 (link)} Data of both HCuSNPs-CpG treatment groups were calculated by subtracting endogenous Cu content from the measured Cu values.