Construction And Performance Study Of Fluorescent Sensors Based On The Skeleton Of Cyanine Dyes

As an important analysis and detection method,fluorescent biochemical sensors have been widely used in important fields such as biological analysis,environmental monitoring,and clinical diagnosis because of their high sensitivity,good selectivity,temporal-spatial resolution,and easy operation.It can not only perform qualitative or quantitative analysis of target substances by detecting the change of fluorescence signals,but also can be combined with fluorescence imaging technology to realize in-situ and real-time monitoring of target substances in vivo,which provides an important means for studying physiological effects of target substances in vivo.So far,organic fluorescent biochemical sensors have developed more maturely,but they still face challenges such as short detection wavelengths and biocompatibility to be improved.It is still an important issue to enrich and develop new excellent fluorescent sensors.Based on the advantages of long fluorescence emission wavelength and good water solubility of cyanine dyes,this project constructed fluorescent probes for the specific identification of nitroxyl（HNO）and biothiols and designed and synthesized leucine aminopeptidase-activatable anti-cancer prodrug molecules using cyanine derivative CHMC as the parent.The specific content is as follows:（1）Based on the reaction mechanism of triphenylphosphine structure and HNO,a HNO fluorescent probe CHMC-N-P with good biocompatibility has been constructed by grafting it on the cyanine dye parent CHMC.The probe can specifically interact with HNO and separate the triphenylphosphine moiety to restore fluorescence,thereby realizing the detection of HNO.The probe’s response to HNO shows a significant fluorescence enhancement（～17 times）,a lower detection limit(1.17×10^-8 M),a faster response rate（～7 min）and better selectivity,Meanwhile,it shows good water solubility and cell membrane permeability.Finally,we successfully applied the probe to the detection and fluorescence imaging of HNO in human cervical cancer cells（He La cells）.（2）A novel fluorescent probe CHMC-N-S has been constructed by using CHMC fluorescent dye as the parent,introducing 2,4-dinitrobenzene sulfonate into its active site hydroxyl group,and using the strong electron withdrawing effect of 2,4-dinitrobenzenesulfonyl group to quench the fluorescence of the parent CHMC.The probe can specifically interact with biothiols and give a strong fluorescent signal at 639 nm,finally realizing the detection of biothiols.CHMC-N-S shows the advantages of faster response speed,higher sensitivity and better water solubility in the identification of biological thiol compounds.This probe provides a new option for the monitoring of biothiols in vivo.（3）Based on the overexpression of leucine aminopeptidase（LAP）in tumor cells,we use leucine residues as the recognition target,CHMC as the fluorescent signal output group,and camptothecin（CPT）as the target to kill tumor cells,trying to design and synthesize a prodrug CHMC-Leu-CPT that releases anti-cancer drugs by LAP trigger.We hope that the prodrug can be specifically activated by LAP in tumor cells,and release anti-cancer drugs to selectively kill of tumor cells,finally providing a new reference for the diagnosis and treatment of related diseases.