Construction And Recognition Properties Of Mitochondria-targeted Triphenylamine Molecular Probes

In the complex biological microenvironment,active small molecules such as glutathione（GSH）,cysteine（Cys）,reactive oxygen species（ROS）,reactive sulfur（RNS）,anions and metal ions play an indispensable role.However,once their concentration in the organism exceeds their physiological needs,it may cause irreparable damage.Therefore,it is very important to effectively monitor the dynamic changes of active small molecules and anions and cations in organisms.In recent years,fluorescent probes have gradually attracted the attention of researchers due to their advantages of high sensitivity,convenient operation,good selectivity,and spatiotemporal resolution.Currently,they have been widely used in fields such as biological monitoring and medical research.On the other hand,fluorescent probes generally use fluorescent groups（such as triphenylamine,coumarin,cyanine,etc.）as the mother nucleus,and then generate corresponding derivatives through various reactions to enable them to recognize certain active molecules.Fluorescent probes with large Stoke shifts are increasingly favored by researchers due to their advantages such as low background interference,deep tissue penetration,and small tissue damage.To this end,we have designed and synthesized several structurally similar triphenylamine fluorescent probes,and conducted a systematic study of their optical properties.The specific content is as follows:（1）In the second chapter,we prepared three probes with similar structures,TPP,TPP-Ben,and TPP-Me,using 4-（diphenylamino）benzaldehyde and3-pyridylacetonitrile as raw materials.These three probes are all inhibited by the TICT process and have high sensitivity to viscosity.However,due to their different electron cloud distributions,their responses to bisulfite salts differ significantly.Only TPP-Me has excellent dual ratio detection performance and can be detected simultaneously.Currently,it has been successfully used in mitochondrial imaging experiments.TPP-Me is expected to be used for efficient and accurate detection and monitoring of bisulfite and viscosity related mitochondrial diseases.（2）In the third chapter,we designed three triphenylamine fluorescent molecules TPP-Br,TPP-Ben,and R1 based on the propeller structure,which enhanced the solubility and mitochondrial targeting ability of the probe by introducing positive charges.We systematically studied the response of three probes to the viscosity microenvironment and found that due to the inhibition of the TICT effect,they all had a significant response to viscosity.However,only TPP-Br had a significant fluorescence signal response to Hg²⁺,which was due to the restriction of molecular rotation caused by the simultaneous coordination of the nitrogen atom on the cyanide group and the bromine atom on the benzyl bromide with Hg²⁺.The recognition of mercury ions by TPP-Br has the characteristics of short response time（10s）,large Stoke shift（195 nm）,strong fluorescence stability,and mitochondrial targeting.Its dual response to viscosity and mercury ions has been successfully used in He La cells.（3）In the fourth chapter,inspired by the properties of the probe TPP-Br in the previous chapter,we designed and synthesized a triphenylamine molecule TPP-Cl containing benzyl chloride.Using probe R3 as a reference object,we systematically compared the optical properties of the three.The results show that TPP-Cl can be used not only for I-detection,but also for"double key"detection of Hg²⁺and Br^-,with a short response time（10s）and a larger Stoke shift（210 nm）.Compared to TPP-Cl,R3does not have these advantages.The construction of a TPP-Cl"double key"fluorescent probe has improved the detection accuracy of Hg²⁺and Br^-in complex biological environments.Through dual encryption,it is expected to achieve accurate diagnosis of mitochondrial related diseases.