Eclipse 80i inverted microscope

Normal C57BL/6 mice and apoE−/− model mice were selected to verify the targeting of the FPD@CD NPs to plaques ex vivo. After air embolization, the left ventricle of the mouse heart was immediately perfused with normal saline. We dissected the thoracic cavity and peeled off the thoracic aorta (from the root of the aorta to the diaphragm of the descending aorta). The FPD@C and FPD@CD NPs (5 mg mL⁻¹) were incubated with the isolated aorta on a shaker for 4 h at 37 °C. Then, the isolated aortas were washed with PBS three times, further embedded in paraffin and sliced serially (5 μm), stained with a Prussian blue staining solution (20% hydrochloric acid and 10% potassium ferrocyanide solution mixture, 1:1 volume ratio) for 1 h, counterstained with a nuclear fast red solution for 5 min, and washed with distilled water, dehydrated and sealed. Images were acquired with an optical microscope. For immunofluorescence staining, aortas incubated with DiI-FP@CD (5 mg mL⁻¹) on a shaker for 4 h at 37 °C were embedded in optimal cutting temperature compound (OCT) in blocks and placed in a −80 °C freezer. The sections were cut with a cryotome (5 μm) and stained with the F4/80 antibody. Nuclei were counterstained with DAPI. Images were captured with a Nikon Eclipse 80i inverted microscope (Nikon, Tokyo, Japan).