Fig. 2

Imaging of dual tracer-labeled exosome-mimetic nanovesicles. Exosome-mimetic nanovesicles [14] were labeled with DiI and ^99mTc-HMPAO simultaneously. a Ex vivo fluorescence image acquired 3 h after the intravenous injection. Nanovesicles accumulated in the liver, intestine, kidneys, and brain. b SPECT images acquired in vivo at 0.5 and 3 h after the intravenous injection. In this specific example, the accumulation pattern was different from fluorescence imaging, showing that the nanovesicles accumulated mainly in the liver and spleen and were few in the intestine. Simultaneous labeling revealed a different distribution which might be partially caused by the differences of behavior of tracers after vesicles degraded in their initially retained tissues