Fig. 4

In vivo evaluation of pPhD NPs in orthotopic oral cancer models. a NIRFI images and b quantitative fluorescence with statistical analysis of the ex vivo distributions (n = 3) of the nanoparticles. c Chemical structures illustrated the chelation of the manganese(II) ions (Mn²⁺) to PhD molecules. d Concentration-dependent relaxation of Mn²⁺ chelated pPhD NPs. The Mn²⁺ chelated in pPhD NPs were 0.008, 0.016, 0.08, 0.16 and 0.8 mM, respectively. L denotes the low concentrations started at 0.008 mM, H denotes the high concentrations ended at 0.8 mM. e T1-weighted MRI images of time-dependent tumour accumulations (n = 3) of the nanoparticles acquired on a 7 T MRI scanner and f the quantitative MR signal intensity changes (I/I₀) on orthotopic oral cancer model. I is MR signal at a specific timepoint, I₀ is the MR signal of the mice at Pre timepoint. Pre denotes the mice before Mn²⁺ chelated pPhD NPs treatment. g Photothermal effects of the nanoparticles on orthotopic oral cancer model (n = 6). The laser (680 nm) dose was 0.4 W cm^–2 for 3 min. h Fluorescence imaging of ROS productions within tumour tissues and i quantitative comparisons with statistical analysis of different treatments on orthotopic oral cancer model (n = 3). The laser (680 nm) dose was 0.4 W  cm^–2 for 3 min. The ROS productions were indicated by NIRF ROS probe, CellROX. Pre denotes the NIRFI before CellROX treatment; Post means the NIRFI after CellROX indication. j Phototherapeutic effect monitored by MRI. The laser (680 nm) dose was 0.8 W cm^–2 for 3 min. Pre denotes the MRI of the mice before treatment with Mn²⁺ chelated pPhD NPs. For all animal experiments above, the injection doses of upPhD and pPhD NPs were 10 mg kg⁻¹ (calculated based on the concentration of PhD monomer). Phy was 5.3 mg kg⁻¹. *p < 0.05; **p < 0.01; ***p < 0.001. The units of the gradient bars are all given as arbitrary unit (a.u.) to present the fluorescence or MRI signal intensities are relatively higher or lower. All error bars are presented as standard deviation