Fig 3. Tumor uptake of the affibody molecules by subcutaneous xenografts.

Mice bearing C666-1 xenografts (circles) were intravenously injected with Dylight755-labeled affibody molecules followed by dynamic scanning with in vivo NIR system. The unselected original affibody scaffold molecule Z_WT with no binding affinity to LMP-2 served as a control. The fluorescence signal in xenografts were detectable at 0.5 h post-injection. Subsequently, the fluorescence intensity in the tumor gradually increased until 4~ 6 h post infection and then decreased gradually. The fluorescence signal of Z137 and Z142 at tumor sites persisted for at least 48 h. In addition, affibody accumulation in the kidneys was observed because the small size of affibody proteins are cleared via renal filtration. No tumor-specific fluorescence signal was observed in the xenografts in the mice injected with Dylight755-labeled Z_WT molecules.