Considering the relatively high fluorescence quantum yields (Table ) at the same mass concentration (1 mg/mL), we chose PPC15 and PPC20 NPs to evaluate their performance for fluorescence imaging in Please do not adjust margins Please do not adjust margins vivo (Figure ). Both of two NPs showed low cytotoxicity (Figure ) and excellent blood compatibility in vitro (Figure ). For fluorescence imaging in vivo, an aliquot of PPC15 and PPC20 NPs with a dose of 25 μg/g was intravenously injected via tail vein to a mouse bearing a xenografted tumour model of 4T1 or HepG2.