Fig 1.
Schematic illustration of the presumed connection of Prussian blue nanoparticles (PBNPs) with and without coating and the particle conjugation by IR820.
The blue halo around the PBNPs represent the non-biocompatible PBNP-species (PB-HCl) acting as a coating surface. The colors represent the following ions or atoms, respectively: blue: Fe (III); orange: Fe (II); black: C; gray: N.
Fig 2.
Atomic force microscopy (AFM) amplitude-contrast images with different magnification of PBNPs on mica surface.
PBNPs on AFM images as objects with a flat rectangular surface protruding from a rounded halo. The rectangular surface represents the real geometry of the particles while their halo is the consequence of tip convolution. Rectangularity of the particles (together with their halo) was found to be 0.774 ± 0.111 (mean ± SD), indicating that PBNPs indeed represent rectangular topography. The height of the particles was 36.457 ± 9.496 nm (mean ± SD). The size of the images are 4.125 μm x 4.125 μm (Fig 2A), 2.5 μm x 2.5 μm (Fig 2B and 2C) and 250 nm x 250 nm (Fig 2D) respectively.
Fig 3.
TEM images of PBNPs on carbon-coated copper grid.
PBNPs appeared flat rectangular, dense objects. The mean diameter of the nanoparticles was 30.14 ± 10.656 nm (average ± SD). The smaller objects on the image are individual PBNP particles which are not conjugated into the final PBNP complex. Scale bar is 500 nm.
Fig 4.
Axial T1-weighted MR images of a mouse (A) before and (B) after intravenous administration of Prussian Blue. Red arrows indicate that regions where signal intensity changes happened. Enhanced signal intensities were registered in the lungs, liver, kidneys, and abdominal vessel, which supports the results of a previous publication [47].
Fig 5.
White and fluorescent images of a mouse (A) before and (B) after intravenous administration of Prussian Blue (images from left to right: prone white, prone fluorescent, supine white, supine fluorescent images) at 690 nm. After the PBNP administration enhanced dye concentration was registered in the head and thoracic region based on the high dye content of the circulation system, furthermore the images illustrated the liver of the animal. The images are highlighted on the same dynamic color look-up table, which illustrates the signal intensity with different tone from cold to hot colors.