Near-Infrared Fluorescent Probes Based On Xanthene Dyes:Design,Synthesis And Application In Bioimaging

Fluorescence imaging has become one of the most important means of monitoring biological cells and biological processes.Xanthene dyes are widely used in the development of small molecule near infrared fluorescent probes.In this thesis,two near-infrared xanthene fluorescent probes were designed and synthesized by introducing specific recognition group,which were successfully applied to fluorescence detection and imaging of disease markers.The main research works and results are as follows.Firstly,a near-infrared fluorescent probe RB-Phenyl acrylate?NOF1?for high selectivity and high sensitivity detection of cysteine?Cys?was designed and synthesized.A novel near-infrared xanthene fluorescent probe NOF1 based on acrylate group as a recognition unit for detecting Cys was synthesized.The results of UV-absorption spectroscopy and fluorescence spectroscopy indicateded that the NOF1 probe showed good selectivity for cysteine and can efficiently distinguish between homocysteine?Hcy?and glutathione?GSH?.Fluorescence intensity has a fine linear fit between a range of cysteine concentration with a LOD as low as 210 nM The response mechanism of NOF1 to Cys was determined by absorption and fluorescence spectroscopy,HRMS and time-dependent density functional theory?TD-DFT?calculation.In addition,the probe NOF1has good sensitivity and selectivity for the detection of cysteine in human plasma,and the spiked recovery is in the range of 96.9%¹04%.Importantly,the probe NOF1 was successfully applied to the near-infrared fluorescence imaging of cysteine in living cells,zebrafish and mice.Secondly,a near-infrared fluorescent probe RB-Phenyl diphenylphosphinate?NOF2?for fluorescence imaging of peroxynitrite was designed and synthesized.A novel near-infrared fluorescent probe?NOF2?for endogenous peroxynitrite?ONOO^-?detection was designed and synthesized by introducing a phosphinate group[-P?O?Ph₂].The maximum absorption wavelength of probe NOF2 to ONOO^-is about 680 nm and the maximum fluorescence emission is in near infrared region??em=742 nm?The NOF2 probe has good selectivity and sensitivity to peroxynitrite,linear concentration range 0-40?M,a detection limit as low as 400 nM.In addition,the response mechanism of the probe NOF2 to ONOO^-was confirmed by HRMS and time-dependent density functional theory?TD-DFT?calculation.The NOF2 probe possesses good biocompatibility and low toxicity.The probe NOF2 was successfully applied to fluorescent imaging for ONOO^-in live cells and in a mouse model of inflammation.