The Synthesis And Application Of Nucleus-Targetable Fluorescent Probes

Bio-technologies which based on fluorescent probes are more and more significant in life science field. With the rapid development of bio-imaging technologies, fluorescent probe has already became the important tool to study the medicine and biology issues. To this date, most researchers concentrated their studies on the fluorescent probes, which are targetable to the subcellular structure and can give the quantitative information. Nucleus is the cell control hub, which plays an irreplaceable role in cell metabolism, growth, differentiation, and other processes. Although quite a few fluorescent probes have been reported to show high affinity to DNA in buffer, only a very limited number of them can stain the nucleus specifically in living cells. So the development of a nucleus-targetable fluorescent probe, which has a specific function is very important. In this paper, based on commercial Hoechst dye, we designed and synthesized three fictionalized nucleus-targetable fluorescent probes, and preliminary evaluated their properties and applications through preforming some experiments.We have developed probe Hoe-NI, by 'Click' connection of a Hoechst unit and a naphthalimide dye. This probe emits dual fluorescence bands centered at 450 nm and 505 nm. In buffer solution, Hoe-NI shows sensitive ratiometric detection of DNA concentration, and is used for the evaluation of DNA damage by hydroxyl radicals. Hoe-NI also exhibits the specifically and wash-free staining of living nucleus in all the tested cells, including L02, SMMC-7721, COS-7, MCF-7, Hela, raw 246.7 cells. Most importantly, Hoe-NI, is first probe applicable for two-channel ratio imaging of nucleus DNA content in living cells, which has been demonstrated by the visualization and the quantitative analysis of nucleus DNA damage induced by hydroxyl radical.O-phenylenediamine (OPD) is known to react with nitric oxide (NO) to generate a triazole structure. Impaired from this, we designed a nucleus-targetable fluorescent probe Hoe-NO based on commercial Hoechst dye. Probe Hoe-NO can interact with DNA in buffer solution, which indicated that it can be targeted into nucleus. The NO titration experiment was performed and the high-resolution mass spectroscopy (HRMS) verified the target triazole structure generation. The confocal microscopic imaging showed that Hoe-NO can stain the nucleus in living cells, with low background fluorescence. Probe Hoe-NO also has two-photon property which can be used in fluorescence lifetime imaging (FLM). So we compared the nucleus FLM of Hoe-NO before or after the addition of NO, and found that the fluorescence lifetime of Hoe-NO increased after treated with NO.We have developed probe Hoe-Indol, by inducing quaternary ammonium salt into Hoechst unit. DNA titration experiment showed that probe Hoe-Indol can interact with DNA which indicated that it can be targeted to nucleus. The viscosity experiment demonstrated that probe Hoe-Indol has a potential advantage in detecting solution viscosity. The confocal microscopic imaging showed that probe Hoe-Indol could stain the nucleus in living cells, with low background fluorescence. So, probe Hoe-Indol can be used to detect nucleus viscosity in living cells.