Figure 3.

(a) A photograph of the dorsal side of the immunodeficient mouse, bearing a grafted subcutaneously SK-BR-3 tumour 15 days post-implantation. A PBS solution of FMN and UCNPs was injected peritumourally. The tumour area is marked by a (blue) rectangle, its zoomed-in images spectrally filtered to emphasise FMN and UCNPs emissions are shown in insets labelled FMN and UCNPs, respectively. In FMN and UCNP images, the tumour exhibited contrast of 2 and 30, respectively, demonstrating the superiority of UCNP-assisted imaging. (b) A plot of the SK-BR-3 tumour evolution, showing progressive stable growth of the control tumours (non-irradiated) and tumour regression post-PDT treatment (black arrow, day 15) using FMN + UCNPs. (c) A time-lapse series of the bright-field photographs of the SK-BR-3 tumour area taken prior to the 975-nm laser treatment “15”, 25 and 50 days after treatment and the photographs of appropriate controls. Scale bar, 10 mm. (d) Histological images of the tumour tissue sections stained with hematoxylin and eosin, excised 1 day after the 975-nm PDT treatment. FMN + UCNPs in PBS solution were injected peritumourally in the control and PDT treated tumours. FMN + UCNPs after irradiation display profound hemorrhages, respectively, whereas control shows no abnormalities. Scale bar, 100 μm.