Fabrication,Performance Control And Application Of Intelligent Ag/Pb-based Semiconductor Multifunction Optical Nanoprobes

As a third organism signaling molecule,hydrogen sulfide(H₂S)is involved in a variety of metabolic and biological tissues,which also affects various physiological and pathological functions.The endogenous H₂S is mainly produced by three specific enzymes such as cystanthionine-?-synthetase(CBS),cystathionine-g-lyase(CSE)and3-mercaptopyruvate sulfur transferase(3-MST)via catalyzing cysteine and cysteine derivatives.For colorectal cancer,due to the over-expression of CBS in cancer cells,the concentration of H₂S in the tumor microenvironment is much higher than normal tissues(0.3-3.4 mmol/L).Therefore,a specific detection method using H₂S as an intelligent activator is emerged,providing novel opportunity for specific/sensitive diagnosis of colon cancer.In addition,due to the low biological tissue damage and deep tissue penetration of the second near-infrared(NIR-?,1000-1700 nm)regions,NIR-? optical imaging has regarded as the new generation indispensable non-invasive diagnosis technology.At the same time,photoacoustic(PA)imaging,as an emerging imaging detection technology,has a higher penetration depth than optical imaging,which attracts great attention.However,traditional single-modal imaging technology is usually impossible to provide comprehensive information for accurate tumor diseases diagnosis.Therefore,integrating NIR-? fluorescence and PA imaging into one nano-diagnostic platform is highly desirable for constructing a complementary multi-mode optical diagnostic probe with more comprehensive information and higher detection sensitivity/signal-to-noise for tumor diagnosis and treatment.To this end,in this thesis,we will design the H₂S-triggered Ag/Pd-based intelligent NIR-?/PA multi-modal nanoprobe for in-situ accurate diagnosis of early colorectal cancer.The main research contents are as following:(1)Intelligent Si O₂@Ag NIR-?/PA dual-modal nanoprobe was designed by coating Ag nanodots on Si O₂ nanospheres.After S^2-sulfurization,Si O₂@Ag was successfully transformed into a Si O₂@Ag₂S nanoprobe with excellent photothermal conversion efficiency and high-efficiency NIR-? emission.And PA and NIR-? fluorescence imaging of S^2-in vitro was systematically evaluated,revealing the high detection limit(0.92 n M)of S^2-and laying the foundation for realizing highly sensitive PA/NIR-? diagnosis of colorectal cancer in vivo.(2)The in vivo application of Si O₂@Ag nanoprobes modified by polyethylene glycol(PVP)was further evaluated,and the mechanism of the in-situ reaction of Si O₂@Ag nanoprobes was systematically explored.The in vivo PA/NIR-? dual-modal specific diagnosis of early colorectal tumors was realized,providing new idea for the development of specific multi-modal diagnosis of colorectal tumor.(3)In order to further improve the accuracy and sensitivity of S^2-detection,a new strategy of S^2-optical detection based on Pb-based semiconductor was proposed.By coating Si O₂ on the outer layer of Cs Pb X₃(X=Cl,Br)perovskite,the water-soluble Cs Pb X₃(X=Cl,Br)@Si O₂ nanoprobe was successfully constructed.And highly sensitive detection of S^2-was achieved in NIR-? region with a detection limit of0.32 nM.