Cellular concentration of Dox and copper after treatment of NDL cells for 30 min on ice with: released CuDox, free Dox, or CuDox-LTSLs. Concentration of Dox (a, b) and copper (c, d) in cells incubated with various treatments and 0.5, 4 and 24 h incubation at 37°C in pH 7.3 media (a, c) or pH 6.3 media (b, d). Relative cellular Dox and copper concentrations from cells incubated with released CuDox (e, f) at 0.5, 4, 24 h after incubation at 37°C in pH 7.3 (e) and pH 6.3 (f) media. Statistical analyses were performed using one-way ANOVA followed by a Tukey Post Hoc test in a-d and Student’s t-test in e-f. *p < 0.05, **p < 0.01, ***p < 0.001.