TR-cubes
as an effective in vivo heat mediator and controlled drug
delivery system. (a) Scheme of the in vivo efficacy study. (b, c)
Infrared images showing the heating of DOXO-loaded-TR-cubes at day
1 (b, MH1) and day 3 (c, MH3). (d) Plot of the temperature difference
(ΔT) between TTumor (white circle) and TSkin (black circle),
showing a 15 °C rise after MH1 and 10 °C after MH2 and MH3.
(e) Photos of the animal after TR-cube injection (left animal),
after the first MH cycles (middle), and at 90 days (right animal).
Mice treated with DOXO-loaded-TR-cubes + MH showed complete tumor
suppression by day 90 post-treatment (color coded inserts show enlarged
images of the tumor). The photos of the three mice do not correspond
to the same animal. (f, g) Histological sections of tumor treated
with TR-cubes alone (f, intact stroma) or DOXO-loaded-TR-cubes + MH
(g, thin stroma) stained with Prussian Blue for iron and Fast Red
dye for collagen. (h, i) Tumor growth curve and Kaplan−Meier
survival plot showing the difference in tumor suppression and improved
survival between the DOXO-loaded-TR-cubes + MH and the other groups
studied. The DOXO-loaded-TR-cubes + MH group in the tumor growth curve
showed significant improvement in tumor suppression in comparison
to the control group (with p = 0.0002 (***)), the
standard DOXO group (p < 0.0001 (****)), and the
DOXO-TR-cube group (p = 0.0035 (**)). (j−l)
Confocal images of the whole tumor slice, which was sacrificed 30
days post treatment, showing the presence of viable cancer cells (DAPI
blue staining) and DOXO (red signal, shown in pink due to the merge
with DAPI) for DOXO* (j), DOXO-loaded TR-cubes (k), and DOXO-loaded
TR-cubes + MH (l). The scale bar represents 0.5 cm.