Figure 2.

3D re-construction of multiphoton microscopic images taken from an 8 mm³ tumor tissue block collected from 4T1 tumor-bearing mice co-injected with active targeting FITC-Tf-uIONPs (green) and non-targeting TRITC-uIONPs (red) at different time points (A and G for 1 hour, C and I for 3 hours, E and K for 24 hours after injection) with the selected cross-sections (B and H for 1 hour, D and J for 3 hours, F and L for 24 hours). Tumor collagen was visualized using second harmonic generation (SHG), and presented as bright signals in a grayscale setting. The scale bar for all images is 50 µm.