Construction Of Novel Xanthene Dyes And Their Application In Fluorescent Probes

The fluorescence signal of rhodamine dye in visible region limits its application in fluorescence imaging.We modified the molecular structure of xanthene fluorescent dye.Then,this paper carried out the design and synthesis of NIR fluorescent dyes and the construction of fluorescent probes.We hope to solve some thorny problems in the design of organic small molecule fluorescent probes for xanthene fluorescent dyes.this paper mainly carries out the following work:（1）A novel xanthene fluorescent dye BNX was synthesized.The dye BNX has a far-red absorption wavelength of 603 nm and a near-infrared fluorescence emission wavelength,and has excellent photophysical properties and low cytotoxicity.In addition,a novel fluorescent NADH probe was further developed based on the fact that BNX was methyl esterified and had a double positive charge structure capable of receiving electron.After the probe was reduced by NADH,the maximum absorption wavelength shifted from 604 nm to 570 nm,and the fluorescence signal at 637 nm was gradually quenched.Cell imaging experiments shown that the probe has good water solubility and less cytotoxicity.It can be used for fluorescence imaging detection of exogenous and endogenous NADH.（2）In order to change the push-pull electron system of rhodamine structure and improve the photophysical properties of traditional rhodamine dyes,thiophene was used as a relay to construct an xanthene fluorescent dye BTPX with twin spiral ring structure.BTPX has a near-infrared absorption wavelength（702 nm）and fluorescence emission wavelength（737 nm）,and has good membrane permeability,biocompatibility and low toxicity and providing a good material basis for their biological applications.Using spironolactone “off-on” to control the fluorescence signal “off-on” mechanism,a probe STPXN with enhanced red emission fluorescence was further developed,according to single spironolactone product STPX was raw material for fluorescence imaging detection of intracellular copper ions.The probe has rapid response to copper ion,high sensitivity and detected concentrations as low as 28 n M.