The results indicated that mice treated with EGF-PLGA@5Fu/PFC NPs exhibited obviously stronger fluorescence signal at the tumor site than that observed in response to PLGA@5Fu/PFC NPs (Fig. 4a), which may have been due to EGF-mediated accumulation at tumor sites, and internalization of these NPs via ligand-receptor mediated endocytosis. Here, EGF is linked to neoplasm.