Figure 5. Gd@C₈₂(OH)₂₂ nanoparticles effectively eliminate CSCs and tumour initiation.

(a,b) MDA-MB-231 cells were cultured in adherent monolayer culture or ultra-low attachment dish for 10 days, and treated with PBS, Paclitaxel (5 or 10 nM), Gd@C₈₂(OH)₂₂, C₆₀(OH)₂₂ or GdCl₃ (all 50 μM) for another 24, 48 or 72 h. The cell viability was determined (mean±s.e.m., n=3 each). *P<0.05 (two-way ANOVA, Bonferroni’s post-hoc test). (c) Tumoursphere formation of MDA-MB-231 cells after treatment for 21 days (scale bar, 100 μm). (d) The tumourspheres were quantitated (mean±s.e.m., n=3 each). To tumourspheres of 70–150 μm, **P<0.01; to tumourspheres of >150 μm, ^##P<0.01 (one-way ANOVA, Tukey’s post-hoc test). (e) mRNA levels of CSC markers were analysed by qPCR (mean±s.e.m., n=3 each). *P<0.05 (one-way ANOVA, Tukey’s post-hoc test). (f) A total of 1 × 10⁶ MDA-MB-231 cells were injected into the right back flanks of the mice s.c. Mice were monitored and treated daily. mRNA level of CSC markers in tumour tissue were analysed by qPCR (mean±s.e.m., n=3 each).