QDs are selectively taken up by microglia in vivo. A-D. QDs were stereotaxically injected into the hippocampus of CX3CR
+/- mice, which express GFP in microglia. A. Representative photomicrographs showing the distribution of QDs in the hippocampus. B. GFP-labeled microglia in the hippocampus. C. Merge of (A) and (B) shows that the majority of QDs were localized in microglia. Scale bar, 200 μm. D. Higher magnification image of the boxed area in (C). Scale bar, 20 μm. E. Representative confocal image through a single plane of quantum dots (red) internalized by microglia (green) in the hippocampus of CX3CR
+/- mice. Blue: DAPI. Scale bar, 20 μm. F, G. QDs (red) were not taken up by astrocytes labeled with anti-GFAP (green, F) or neurons labeled with anti-MAP2 (green, G) after they were injected into the hippocampus of C57Bl/6 wildtype mice. Scale bar, 20 μm.