Design And Synthesis Of Nucleic Acid And Mitochondria Dyes With Improved Photostability

The study of organelles is an important mean to recognize the structure and function of cell. In recent years, fluorescent technology has been widely used in bioimaging, biosensing, medical diagnosis and environmental detection. With the development of technology, chemistry and biology face a lot of challenges, and fluorescent dyes for organelle applied to fluorescence microscopy put forward higher requirements. Many probes for nucleic acids are available, but few of them satisfy multiple criteria, particularly high photostability to endure laser scanning. Many probes for mitochondria are available, but most of them are of low stability, sensitivity to pH, high toxicity and so on. Among the fluorescent dyes, pyrrole boron fluoride (BODIPY) fluorescent dyes which are of high molar extinction coefficient, high fluorescence quantum yield, stable spectral properties, high photostability, a small molecular weight and low toxicity etc., have been widely used as probes for biomolecules and ions and fluorescent dyes for organelles (endoplasmic reticulum and Golgi apparatus). However, the dyes based on BODIPY for mitochondria in living cells were rarely reported in recent years. The main objective of this thesis is the design and synthesis of nucleic acid and mitochondrial dyes with more excellent performance to satisfy multiple criteria.We report a cyanine dye TO3-CN for the first time, synthesized by introducing a CN group to the trimethine chain of the classical red emitting TO-3dye to improve its photostability, as well as their spectral properties and interaction with nucleic acids. TO3-CN shows excellent light fastness and a large fluorescence Stokes shift (more than40nm). Because of its sensitive fluorescence response to nucleic acids with a large fluorescence quantum yield (more than0.7) and low cytotoxicity, this dye may be a potential candidate for nucleic acid detection in vitro and intracellular fluorescence imaging.A BODIPY-based dye OBEP has been developed to act as a mitochondrial fluorescence probe. This dye is of high stability, low toxicity and insensitive in a pH range as wide as pH2-10. Its uptake into mitochondria is independent of mitochondrial membrane potential in living cells. OBEP can label swollen mitochondria resulting from different degrees of cell damage in light and resist fading even after12h of incubation.On the basis of the dye OBEP, red fluorescent sOBEP and near-infrared fluorescent dOBEP have been developed. Both of them, particularly the near-infrared fluorescent dye dOBEP, have high light stability which could compare with OBEP. Their uptake into mitochondria is independent of mitochondrial membrane potential in living cells. Thus, a series of BODIPY-based mitochondrial dyes with orange to near infrared fluorescence have been developed.