Fig. 1.

Optical microscopy of AβPP/PS1 and control mouse brains. A) IHC stained cortical section (7 μm thick) of the fixed brain from a transgenic mouse used in these studies. Plaques stained brown with antibodies against human Aβ. The positive DAB signal at the cortical surface could represent some BBB leakage allowing passage of mouse IgGs. Scale bar = 1,000 μm. B) Control brain section from a wild-type mouse showing a complete lack of IHC positive regions. Scale bar = 1,000 μm. C) Section from the brain of a transgenic mouse stained in vitro for iron using Perl’s reagent demonstrating binding of our anti-AβPP conjugated SPIONs to plaque. Scale bar = 20 μm. D) Control brain section from a wild-type mouse demonstrating the lack of blue staining when incubated with the same SPIONs as in (C). Scale bar = 20 μm. E) Perl-stained section of a brain from an AβPP/PS1 transgenic mouse that was injected with anti-AβPP SPIONs. Note the large plaque with its associated SPIONs (arrow). Scale bar = 20 μm. F) Thioflavin-S stained brain section from a transgenic mouse demonstrating the presence of plaques as green regions. Scale bar = 10 μm. G) IHC of a cortical brain section stained for AβPP with the anti-AβPP antibodies used to modify the SPIONs showing plaque detection similar to (A). Scale bar = 10 μm. H) Perl’s stain for iron in an AβPP/PS1 brain showing no iron detection (Compare with (C)). Scale bar = 10 μm.