Design And Application Of Long-wavelength BODIPY Fluorophores

As the micro-imaging technology develops rapidly, the fluorescent analysis based on fluorescent dyes has become an increasingly important method in the field of life science. Long-wavelength fluorescent probes show great potential for applying in living system, as long-wavelength (600-900 nm) excitation and emission have the advantages of minimum photodamage to biological samples, deep tissue penetration, and minimum interference from background autofluorescence by biomolecules in living systems. It has been a research hotspot to develop new fluorophores with long emission wavelength and their application in life science. In this research, a few long-wavelength fluorephores were designed and they were further applied in fluorescence bio-imaging field.1. Two aza-BODIPY derivatives DPDTAB and TTAB were synthesized by replacing the phenyl rings with thiophene in the original 1,3,5,7-tetraphenyl aza-BODIPY. Significant bathochromic shifts were achieved with a longest emission wavelength up to 757 nm. The data of X-ray crystalgraphy, DFT calculations, and electrochemical investigations ascribed the origin of bathochromic shift to the smaller torsion angles and higher electron donating capability of thienyl groups, which suggests a feasible strategy to develop NIR dyes.2. A series of BODIPY derivatives SPC, DC-SPC, DPC and DC-DPC with tunable long-wavelength emission (600-750 nm) were synthesized conveniently and efficiently. Photo-physical study, non-linear optics study and single-molecular study exhibited their unique properties in far red to near-infrared region, for example, the combination of two-photon excitation and near-infrared emission. Convenient functionalization sites had been reserved in these derivatives, thus they were further functionalized into fluorescent tracker specific for different organelles. Fluorescence imaging studies demonstrated that these trackers could localize in mitochondria, lysosomes or plasma membrane respectively for quite a long time, thus report micro-structure changes of these organelles during physiology, pathology and toxicology processes.3. Two fluorescent LPO probes Lyso-LPO and Ld-LPO specific for lysosome and lipid droplet respectively were synthesized. The conjugovered diene in two probes is sensitive to ROS. After degraded in response to lipid peroxidation, fluorescence emission maximum of two probes shifts from-590 nm to-510 nm. Considering the pathogenesis of atherosclerosis and fatty liver, two probes were used to detect LPO in lysosomes and lipid droplets. Fluorescence imaging and flow cytometry results provided detailed information for the study and early diagnoses of two diseases.4. Two TBET cassettes were constructed by the connections of two different long-wavelength BODIPY dyes to a short wavelength BODIPY dye via a biphenyl linker. Together with the donor molecule, two TBET cassettes with high intramolecular TBET efficiencies (up to 99.9%) and pseudo-Stokes shifts about 70 and 160 nm had been codoped into PS microspheres. Upon exclusive excitation at 480 nm, these microspheres emit simultaneously triple peaks at 512,570, and 656 nm without spectra overlap. This versatile strategy overcomes the problems of intermolecular FRET encoding mode and demonstrates satisfactory performances in confocal imaging and flow cytometric analysis.