Design, Synthesis And Analytical Applications Of Hydrogen Selenide Near-infrared Nano-fluorescent Probes Targeting Different Organelles

Selenium,as one of the the necessary trace elements in human body,is closely related with the repression of the tumor and tumor growth inhibition.Selenide produce highly active small molecules such as H₂ Se through metabolism in the body,then along with DNA damage,protein inactivation or glutathione?GSH?depletion.Na₂SeO₃ was the commonly used tumor treatment,which is widely used in basic research and clinical application,so it's mechanism of action has been the hot topic.As is known to all,lack of oxygen is one of the major features of tumor tissue survival and proliferation.But the previous studies are all under the condition of constant oxygen to experiment,so we research on the condition of lack of oxygen to carry out the mechanism of Na₂SeO₃ inducing tumor cell apoptosis,and we found that Na₂SeO₃ anti-cancer effect is through the important signal molecules H₂ Se in cells produced by the metabolic process,which reveals that H₂ Se increasing causes the apoptosis.However,the anti-cancer mechanism of H₂ Se within cells must be accurate to the organelles level to explore which way to lead to cell apoptosis in Na₂SeO₃ inducing tumor cell apoptosis process.But till now,the H₂ Se produce location in cells and its effect of the apoptosis mechanism is unclear.To illustrate the anti-cancer mechanism,we must study the H₂ Se distribution in the organelles firstly.Based on this,we set up nano target detection platform,developed targetable near-infrared nano fluorescent probes to target three important organelles in cells including the cytoplasm,lysosomes,mitochondria respectively,testing the distribution of hydrogen selenide within different organelles,and carries on the visualization research.It improved the efficacy of anticancer drugs against cancer and accurate treatment which is very meaningful and valuable.It also played an important role to the platform of Na₂SeO₃ and other anti-cancer mechanism of anti-cancer drug research.At the same time,we continue to design and develop the double decteting nano targetable fluorescent probe to detect H₂ Se and O₂^·-in the mitochondrial according to the above results for further research.It provides the necessary research tools to study the Na₂SeO₃ anti-cancer mechanism under the condition of lack oxygen.Our research work mainly include the following two parts:Firstly,we design and synthesis three nanosensors respectively target cytoplasm,lysosomes,mitochondria by using the easily modified advantage of the characteristics of MSNs to detect different organelles H₂ Se in cells and real-time imaging in cytoplasm,lysosomes,mitochondria respectively.We firstly realized the real-time imaging and detection of H₂ Se in organelles level.Mesoporous silica characteristics has good biocompatibility,so we use it to assemble the near infrared molecular probe NIR-H₂ Se,further modified PEI,MPP and TPP respectively to respective target the cytoplasm,lysosomes,mitochondria which are the important organelles,we respectively named cytoplasm positioning nanosensor?Cyto-NIR-H₂Se-MSN?,lysosome positioning nanosensor?Lyto-NIR-H₂Se-MSN?,mitochondria positioning nanosensor?MitoNIR-H₂Se-MSN?.The confocal fluorescence imaging of HepG2 cells induced by Na₂SeO₃ in lack of oxygen shows that higher amount of H₂ Se only accumulated in mitochondria with the increasing time or concentration inducing by Na₂SeO₃,but not in cytoplasm and lysosomes.In the meantime,the H₂ Se burst in mitochondria triggered mitochondrial collapse.Based on these,we reveal that selenite-induced cytotoxicity in cancer cells was associated with the alteration in mitochondrial function caused by high level of H₂ Se.Hence,these MSN-based nanosensors contribute to understand the distribution of subcellular H₂ Se,and thus to elucidation of the functions of H₂ Se at subcellular levels.Secondly,we design and synthesis the double detecting nanosensor to target mitochondria which can detect the high-activity reductive molecule-H₂ Se and the high-activity oxidizing molecule-O₂^·-.Based on the result above,we reveal that it caused by high level of H₂ Se in the mitochondria and damaged the mitochondria after selenite-induced cytotoxicity in cancer cells,so we want to reveal the redox state in the process.Based on this,in order to further study on mechanism of Na₂SeO₃ induced apoptosis of tumor and to study the apoptosis pathway in this chapter,we designed and synthesized a new targeting mitochondrial double location probe?Mito-N-D-MSN?,we firstly assembled on the near infrared molecular probe NIR-H₂ Se to detect the H₂ Se and visible commercial dye DHE to detect O₂^·-,then modified TPP to target the mitochondria,which can implemente the imaging and simultaneous determination of H₂ Se and O₂^·-in the mitochondria.The two molecular probes of NIR-H₂ Se and DHE has clear distinct wavelength which excitation spectra and emission spectra is respectively ?ex /?em = 488 / 638 nm and ?ex /?em = 688 / 735 nm,realized imaging and simultaneous determination in the mitochondria.When Na₂SeO₃ induced liver cancer cells apoptosis with lack of oxygen,we can detect the Redox state synchronization in the mitochondria quantitative detection.Experimental results show that due to the lack of oxygen condition of the entity tumor microenvironment,H₂ Se can't produce reactive oxygen species,then accumulated in mitochondria,caused mitochondrial damage.We preliminarily concluded that Na₂SeO₃ induced liver cancer cells apoptosis under the condition of lack of oxygen go through mitochondrial apoptosis.In the next step,we will further research sodium selenite induced molecular mechanism of tumor cell apoptosis,by using western blot releated with the mitochondrial apoptosis.We hope to find the apoptosis pathway to verify the speculation and solve the problems.