Design And Synthesis Of Novel Luminescent Squaraines For Bio-imaging Applications

The applications of fluorescent dyes cover a wide range of research purposes such as molecular biology, bio-physics, bio-chemistry, clinical diagnosis/analysis and environmental chemistry. This thesis summarizes the design and synthesis of a variety of novel organic luminescent materials and their applications in metal ion probe, bio-imaging. Firstly, in order to meet the different research demands, specific structural modifications were made on the existing luminescent molecules. Secondly, theoretical calculations and spectroscopic experiments were combined to characterize and explain the spectroscopic properties of the solutions and aggregates of the novel molecules. Finally, solutions, micro/nano scale aggregates and dye-loaded polystyrene microspheres are prepared for practical uses. These researches include:1. The design and synthesis of a variety of organic luminescent molecules. I have successfully synthesized many novel luminescentmolecules including oligo(phenylene-vinylene) (OPV), tetraphenylporphyrin (TPP), and squaraine dyes.2. The design and synthesis of a pyrrole substituted squaraine, namely DMPSQ, for the detection of zinc ion. DMPSQ has a turn-on fluorescence response to the existence of zinc ion. The response has a wide linear range, good selectivity and a detection limit as low as 80 ppb. A theoretical calculation and spectroscopic experiment combined approach is used to explain the binding mechanism as well as the spectroscopic responses. The DMPSQ molecule forms coordinates with zinc ion, thereby enhancing the fluorescence emission through the fixation of single bond rotation within the molecule.3. Fluorescent dye loaded polystyrene microspheres (PSMs) are prepared and their application in labeling the stroke sites within mice brain is evaluated. Uniformly sized polystyrene microspheres were prepared and stained with fluorescent molecules such as DMPSQ, BODIPY and DPA. Tissue slicing was used to study the deposition of the microspheres within mice body and the acute toxicity of these microspheres. The PSMs were finally used to trace the blood flow within mice brain, to label the tissue around the stroke site so as to evaluate the application of microspheres in imaging the stroke site.