Preparation And Properties Study Of BODIPY-based Water-soluble Fluorescent Nanoparticles

In the past two decades, BODIPY dyes have attracted much attention of researchers due to their excellent photophysical and photochemical properties. In this thesis, two new silylated BODIPY derivatives were synthesized; their structures and purity were characterized by means of1H NMR, HRMS and elemental analysis. Their optical properties were also investigated. Then, two dyes were covalently incorporated into SiO2nanoparticles separately or simultaneously using the oil in water microemulsion method, which improved the water solubility, biocompatibility and photostability of dyes. The absorption and emission spectra of nanoparticles in water proved that the dye molecules have incorporated into nanoparticles successfully. The TEM images revealed that these nanoparticles did not agglomerate, and were monodisperse with diameters ranging from20to25nm. Dye leakage experiment results indicated that these covalently dye-encapsulated nanoparticles exhibit advantages over physically dye-encapsulated nanoparticles in avoiding dye leakage, which would be helpful for good detection sensitivity and accuracy. In addition, these nanoparticles show less sensitivity of emission to the environment pH, and can be well applied to complex physiological environmentBy incorporating two BODIPY dyes simultaneously at a controlled ratio into the same nanoparticles, silica nanoparticles with tunable emitting wavelengths were realized with a change in the excitation wavelength. Thus by using the dual-dye-doped nanoparticles, two-color imaging was achieved with minimal background signal by employing an appropriate excitation light source and appropriate excitation/emission filter sets. Further, the surfaces of the dual-fluorophore-doped nanoparticles were functionalized with folic acid. The resulting folic acid modified nanoparticles allow for the recognition of HeLa cells which overexpress the folate receptors.