Figure 3. Single QD can be detected in fixed brain slices.

(a) Spinning disk confocal image from a hippocampal region of a 50 μm thick rat brain slice injected with QD (scale bar, 15 μm). The image corresponds to the average of 200 frames. (b) Time behaviour of four different QD (labelled as 1–4 in a), showing that blinking is not synchronized and therefore, not an artefact due to stage vibrations. (c) Blinking behaviour of the fluorescence of a single QD (blue line), of an aggregate of QD (green line, shown with an arrow in a), and background fluorescence (black line). (d) Examples of the fluorescence intensity of QD4 at times indicated with arrows in (c).