Construction And Application Of Mitochondrion-targeted Near Infrared Fluorescent Probe For Hydrazine

Hydrazine(N₂H₄)is considered as a vital industrial raw materialdut to its extensive applications in the manufacture of synthetic catalysts,agricultural chemicals and pharmaceutical products.Nevertheless,due to hydrazine with the properties of high toxicity,mutagenicity,carcinogenicity and teratogenicity,its broad usage will unavoidably result in pollution of enviroment.Besides,the metabolism process of certain drugs can let go hydrazine,such as isoniazid(INH),which cause serious damage to human body.Previous researches has confirmed that hydrazine could cause several adverse effects,including the inhibition of molecular metabolism,mitochondrial oxidation and DNA damage.Therefore,it is of great significance to study and develop an effective method for accurate detection of hydrazine in vivo and in vitro.Comparing with the traditional detection method,as a effective detection technique for hydrazine,organic small molecule fluorescent probe has attracted attention of many researchers due to the strong point such as their easy operatation,high sensitivity,qiuck response rate and real-time monitor.There are many key steps for the research of probe,including the design principles,sensing mechanism and performance.As we know,the molecular structure determines its performance.Therefor,understanding the sensing mechanism is conducive to design the molecular structure meeting our needs,and the investigation on the performance of probe can help to develop the practical application of the probe,which can promote development of the detection technology of fluorescent probe.Consequently,based on the two kind of design principles,here we synthesized two novel organic small molecule near-infrared fluorescent probe in diffieret response model,and studied its detect performance,sensing mechanism and practical application.The details are as follows:(1)Dased on the principle of deprotection,we designed and synthesized a new probe Cy-N₂H₄ with the mitochondrial targeting function,which can detect N₂H₄ by“turn on”response model.Its sensing mechanism was confirmed by high-resolution mass spectrometry and DFT theoretical calculation:hydrazine attacks the carboxy bond of ester on Cy-N₂H₄ to remove the 2-thiophenecarbonyl chloride group,resulting in the rearrangement of electrons in molecule and the restoration of fluorescence(ICT).UV absorption spectrum and fluorescence spectrum show that the probe Cy-N₂H₄ has excellent sensing performance,including good selectivity,low detection limit(14.0 n M)and strong anti-interference ability.Cy-N₂H₄ also shows good practical applicability in practical application experiments such as test strip,silica gel plate and smart phone.In addition,Cy-N₂H₄ was successfully applied to the study of mitochondrial co localization(R=0.93),drug metabolism and tracer imaging of hydrazine.(2)To improve the above work,based on the principle of goup transformation,we designed and synthesized a new probe Cy-FP with the mitochondrial targeting function,which can detect N₂H₄ by“ratiometric”response model.Its sensing mechanism is following:hydrazine attacks the carboxy bond of aldehyde on Cy-FP,connecting with hydrazine molecule,losing a molecule of water and breaking the stable conjugate system of the molecule,resulting in the fluorescence emission wavelength change of Cy-FP from 807 nm to 560 nm.Cy-FP can detect N₂H₄ in both naked eye and fluorescence modes.At the same time,it makes up for the deficiency of Cy-N₂H₄ with only single signal peak,and effectively reduces the interference of background and self fluorescence.The detection limit of Cy-FP is low to 10.3 n M.Cy-FP has good sensing performance and practical application.Moreover,cell imaging studies also show that Cy-FP has good cell membrane permeability and potential for biological diagnosis.