Ligand‐Functionalization of BPEI‐Coated YVO4:Bi3+,Eu3+ Nanophosphors for Tumor‐Cell‐Targeted Imaging Applications

In this study, surface-func- tionalized, branched polyethylenimine (BPEI)-modified YVO4:Bi 3 + ,Eu 3 + nano- crystals (NCs) were successfully syn- thesized by a simple, rapid, solvent-free hydrothermal method. The BPEI- coated YVO4:Bi 3 + ,Eu 3 + NCs with high crystallinity show broad-band excita- tion in the l = 250 to 400 nm near-ultra- violet (NUV) region and exhibit a sharp-line emission band centered at l = 619 nm under excitation at l = 350 nm. The surface amino groups con- tributed by the capping agent, BPEI, not only improve the dispersibility and water/buffer stability of the BPEI- coated YVO4:Bi 3 + ,Eu 3 + NCs, but also provide a capability for specifically tar- geted biomolecule conjugation. Folic acid (FA) and epidermal growth factor (EGF) were further attached to the BPEI-coated YVO4:Bi 3 + ,Eu 3 + NCs and exhibited effective positioning of fluorescent NCs toward the targeted folate receptor overexpressed in HeLa cells or EGFR overexpressed in A431 cells with low cytotoxicity. These re- sults demonstrate that the ligand-func- tionalized, BPEI-coated YVO4:Bi 3 + , Eu 3 + NCs show great potential as a new-generation biological lumines- cent bioprobe for bioimaging applica- tions. Moreover, the unique lumines- cence properties of BPEI-coated YVO4:Bi 3 + ,Eu 3 + NCs show potential to combine with a UVA photosensitiz- ing drug to produce both detective and therapeutic effects for human skin cancer therapy.