Novel Oxazine Fluorescent Dyes And Their Applications In Biological Imaging And Cancer Diagnosis And Treatment

Cell contents usually include organelles,nucleic acids,proteins,sugars and small molecules.Under different physiological conditions,the contents and distribution of cell contents usually have their own characteristics.Detection of the contents and their distribution plays important roles in the prevention and diagnosis of diseases.At present,cancer is one of the important factors of human death.Early detection and diagnosis are very important for patients' cure and survival.Based on the advantages of oxazine dyes,such as good stability,long emission wavelength,etc.,according to the basic principles of fluorescent dyes and photosensitizer design,this dissertation mainly focuses on the exploration and development of fluorescent dyes with high sensitivity,strong targetability as well as excellent photophysics and photochemistry properties to cell contents.The relevant contents are shown as follows.A novel mitochondria targeting fluorescent dye EtNBEn,whose absorption and emssion wavelength are 700 and 720 nm respectively,has been designed and synthesized.Thanks to the oxazine's fluorophore,the dye exhibits excellent properties in good photostability,outstanding chemical stability,NIR absorption and emission.It could be a useful tool to observe the distribution of mitochondria during mitosis and apoptosis in living cells by fluorescence.Furthermore,EtNBEn could be applied to super-resolution microscopy to observe the swelling process of mitochondria under light stimulation.These all demonstrate that EtNBEn has the ability to be further applied to observe the distribution of mitochondria in diverse physiological processes,to contribute to the prevention and treatment of human diseases.An NIR(Near Infrared Ray)fluorescent RNA probe,NBE,was reported for distinguishing RNA from DNA(In cells,the fluorescence intensity ratio between RNA and DNA is 8.7 for NBE and 1.6 for commercial dye)according to the so-called "door-bolt"mechanism,NBE contains a bulky julolidine group that can fit into a spacious RNA pocket and emit intense fluorescence.NBE shows no response to DNA,as it cannot intercalate into the double strands or even enter the DNA minor groove.The sensing mechanism is similar to the mode of a "door-bolt":NBE fits into the RNA "socket" and the fit locks the internal conversion of NBE and turns on the fluorescence.NBE shows outstanding photostability,high selectivity and fast response for RNA,either in aqueous buffers,fixed cells or living cells.The theoretical minimum detection concentration was only 6.67 ng/ml.The probe even can also be utilized to image RNA in live cells to facilitate the judgment of various maladies,such as cancers according to RNA contents.The probe's unique reaction mode has been verified by both TD-DFT theoretical calculations and docking simulations.A novel targeted RNA photosensitizer NBESe was designed and synthesized based on the oxazine dye.NBESe,whose quantum yield of singlet oxygen is as high as 43%,could produce a large number of singlet oxygen under light conditions,which can kill cells.The results of phototoxicity experiment showed that the IC50 value of NBESe was only 60 nM,which has obvious advantages over commercial photosensitizer CE6(IC50 value about 3 ?M)under the same conditions.Furthermore,the results of of tumor bearing mice research showed excellent photodynamic therapy effect,which could be potential market application value.